Vision Screening for Elementary Schools [Reprint 2020 ed.] 9780520340015

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VISION

SCREENING

FOR E L E M E N T A R Y

SCHOOLS

VISION SCREENING FOR ELEMENTARY SCHOOLS

UNIVERSITY

OF

CALIFORNIA

PRESS

THE ORINDA STUDY by Henrik L. Blum, m.d. Henry B. Peters, m.a., o.d. Jerome W. Bett man, m.d.

BERKELEY

AND

LOS A N G E L E S

1959

UNIVERSITY O F C A L I F O R N I A PRESS BERKELEY AND LOS ANGELES, C A L I F O R N I A CAMBRIDGE UNIVERSITY PRESS L O N D O N , ENGLAND ©

1 9 5 9 BY T H E REGENTS O F T H E UNIVERSITY O F CALIFORNIA LIBRARY O F CONGRESS CATALOG CARD N U M B E R :

59-10462

PRINTED IN T H E UNITED STATES O F AMERICA

T o the "Mothers of Orinda" who, through their interest and assistance, contributed greatly to the success of this project.

Preface

T h e importance of good vision to the optimal development and education of all children is widely attested by the laws requiring periodic vision testing of school children. T h e need for good testing methods, essential to effective execution of these laws, has rarely been recognized and acted upon as by the authors of Vision Screening for Elementary Schools. Faced with the need to test the vision of school children in his area, a county superintendent of schools sought advice from his fellow county health officer, who turned to ophthalmologists and optometrists in neighboring universities. All agreed that evidence on the efficiency of existing vision-screening methods was inadequate, and that a promising Modified Clinical Technique developed at the University of California School of Optometry warranted further trial. T h e result was the unusual cooperative research undertaking reported here. Under the leadership of the county health officer, a dedicated interprofessional group designed and carried out a three-year comparative study of vision-screening methods on more than a thousand school children in Orinda, California. T h e study involved the cooperation and talents of parents, teachers, nurses, technicians, school officials, public health officials, optometrists, and ophthalmologists. And before it was completed, the study had received support not only from the University of California School of Optometry and the Stanford University School of Medicine but also from the California State Department of Public Health and the Children's Bureau of the United States Department of Health, Education, and Welfare. T h e Orinda Study clearly suggests two future courses of action. One, further field testing of the Modified Clinical Technique is warranted by this conclusive demonstration of its superior efficiency and low cost. Such field testing should include the application of the administrative recommendations listed in the book. Two, ophthalmologists and optometrists should be stimulated by this example to work together with schools, health departments, and others to plan and conduct vision programs in their communities. Both the clinical evaluations in this study and the questionnaire sent to ophthalmologists and optometrists throughout the United States indicated the extent of common ground beween the two in the field of vision testing. T h e importance of research as a function of official agencies asked to solve probvii

Preface lems in areas of inadequate knowledge and the value of utilizing resources for competent investigation are exemplified by results presented here. Presentation of the study to the American Public Health Association in St. Louis on October 28, 1958, was made on the basis that it is an outstanding example of cooperative research involving a local health department in the United States. T h e ultimate success of this study depends on the extent to which you who read it can adapt the findings to improve the vision of children in your own communities. Chief Bureau of Maternal and Child Health State of California Department of Public Health L E S L I E CORSA, J R . , M . D . ,

V I•I •• I

Acknowledgments

Many persons and organizations contributed time and effort to plan and carry out this study. We particularly wish to acknowledge the splendid cooperation of the Orinda parents and school personnel, without whose help the project could not have been accomplished. This study was supported in part by a grant from the U. S. Children's Bureau. We wish to thank the American Optical Company and the Keystone View Company for technical assistance.

STUDY STAFF Henrik L. Blum, M.D., health officer, Contra Costa County, assistant clinical professor of medicine, Stanford University School of Medicine, and lecturer in public health, University of California, Berkeley; Henry B. Peters, M.A., O.D., associate clinical professor of optometry, University of California School of Optometry; Jerome W. Bettman, M.D., professor of surgery (ophthalmology), Stanford University School of Medicine; Victor Fellows, M.D., clinical instructor of surgery (ophthalmology), Stanford University School of Medicine; Frank Johnson, O.D., clinical instructor of optometry, University of California School of Optometry.

OTHER PARTICIPANTS Education Margaret Bengston, P.H.N., health consultant, Orinda Union School District; Harold Kaar, Ed.D., assistant superintendent in charge of guidance and special education, Contra Costa County schools; Phillip Lambert, Ph.D., assistant professor of education and principal of the Experimental School, University of California, Los Angeles (formerly the assistant superintendent in charge of instruction, Orinda Union School District); Joseph L. Sheaff, M.A., district superintendent, Orinda Union School District; B. O. Wilson, M.A., superintendent of schools, Contra Costa County.

Optometry and Ophthalmology George Bradley, O.D., private practice; Bernice Coler Flom, O.D., formerly of orthoptic department, Stanford University School of Medicine; George ix

Acknowledgments

Hurd, O.D., private practice; Edward Maumenee, M.D., professor of ophthalmology and director of Wilmer Eye Institute, Johns Hopkins Medical School (formerly professor of surgery, ophthalmology, Stanford University School of Medicine). Public Health Nedra B. Belloc, M.A., associate statistician, State of California Department of Public Health; Leslie Corsa, Jr., M.D., M.P.H., chief, Bureau of Maternal and Child Health, State of California Department of Public Health; Phyllis Hecker, M.P.H., program consultant, California Heart Association (formerly statistician); Frederic M. Kriete, M.D., M.P.H., deputy director, State of California Department of Public Health; Theodore Montgomery, M.D., M.P.H., Bureau of Maternal and Child Health, State of California Department of Public Health; Clare S. Winder, P.H.N., public health nurse, Health Department, Contra Costa County. Parents Group The following are all members and officers of the Orinda Mothers Club: Mrs. Robert Creighton; Mrs. F. R. Hildebrand; Mrs. Coleman Huntley; Mrs. William Kooreman; Mrs. E. Starkman; Mrs. David Thaxter.

x

Contents

I II

Review of Vision Screening

1

Design of the Orinda Vision Study

10

III

Definition of Need for Vision Attention: Clinical Criteria

21

IV

Effectiveness of Vision-screening Methods

36

Previous Professional Care and Summary of Vision Status

56

A Longitudinal Study of Changes in Vision Problems, 1954-1956

71

Costs of Screening

89

Supplementary Studies

94

V VI VII VIII IX X

Recommended Design for a Vision Program for Elementary Schools

102

Summary and Conclusions

112

Appendices A. Test-Retest,

Part Tests, and Vision Changes with Age

117

B. State of California Education Code: Pertinent Sections on Vision

129

C. Questionnaires

133

Glossary

139

Bibliography

143

I

Review of Vision Screening

T h e importance of good vision, particularly for the child, should not be underestimated. In the foreword of A Guide for Vision Screening of School Children in the Public Schools of California, Roy E. Simpson states that California public schools make every endeavor to offer equal educational opportunities for all educable persons. T o insure favorable learning conditions for all, appropriate measures are taken to make certain that no pupil is handicapped by physical impairments that can be remedied by treatment, corrected through the use of aids such as eyeglasses, or compensated for through the use of special techniques of instruction.

As one of the senses, seeing affects the performance of the whole child. Vision influences not only the child's performance and adjustment in school activities and in society, but also his health and welfare. T h e relationship between vision and achievement, vision and safety, vision and adjustment, vision and' health, vision and recreation—the significance of the vision problems themselves—is sometimes "lost" in statistical studies. Of course, vision neither operates "all by itself" nor accounts for all the characteristics of the child, but it does play a definite and important role in the performance and health of the child. There is obviously a need to discover those children who have vision problems so that they can receive professional attention. These children can be discovered through vision-screening programs. T h e two main objectives of a vision-screening program for school children are: (i) to detect those children who have vision problems, or potential vision problems, that may affect the physiological or perceptive processes of vision; and (ii) to find those children who have vision problems that interfere with performance in the school. Although these two objectives overlap, they are not identical. Some vision problems may not directly affect school performance and some may affect school performance but not affect the visual health. Children with both types of problems must be detected by the vision-screening program. In other words, it should detect those children who, because of their visual mechanisms, have performance handicaps; detect those children who have visual anomalies that may become performance handicaps at some future time; and detect those children with eye-health problems who should be under professional observation or treatment. 1

Review of Vision Screening In general, the problems that should be identified in a screening program can be classified as: vision problems, including poor visual acuity, significant refractive error, and faulty coordination; and organic problems, including pathology and anomalies of the eye, adnexa, and impaired visual pathway or neuromuscular mechanism. Both kinds of problems must be detected if the screening program is to accomplish its main objectives. In the identification of children with vision problems through screening, there are two secondary objectives that should be considered. One is to use the information gained through vision screening to help children who have vision problems. It is important that this kind of information be available to school personnel, because it should be considered in counseling the child (and the parents of the child) with a vision problem. A vision problem may limit the performance expectation of the child and the career opportunities open to him. Certainly some of the partially sighted children need very careful guidance and personal attention. For those with congenital or inherited defects, factual information is needed so that the children can be made to understand their own problems. T h e other secondary objective is to gather information regarding vision problems, their incidence, changes in vision status, and so forth. There are still many unanswered questions concerning the vision problems among school-age children, and a comprehensive vision-screening program can contribute greatly to both future research and the understanding and care of these children. In the Sight-Saving Review (spring, 1957, pp. 35-36) it is stated that: " T h e ideal goal is that every child should have a thorough professional eye examination before entering school." Since an eye examination is not given to every preschool child now, and is probably not practicable, vision screening must fill this need. Vision screening, which must give information rapidly, economically, and on large numbers of children, is not group or "mass" testing, but abbreviated testing of individuals. Wherever vision screening is done, there is always a "third-party" interest— that is, someone else wants to know about the vision capacities of a particular child. T h e school people who have to plan an educational program for a child want to know about his vision capabilities. There does not have to be a felt need, as there is in a clinical situation. There does not have to be an appreciation on the part of the child that he needs vision testing. T h e vision screening is given to all the children, regardless of symptoms or performance, unless the school administrator is specifically instructed not to do so by the child's parents. It is important to realize that there is an essential difference between visionscreening test scores and clinical data. T h e two results are obtained under different conditions. In the clinical situation, physiological control is used in obtaining data. When the optometrist or ophthalmologist measures visual coordination, for example, the focusing system of the eyes is under physiological and other controls. In the screening situation, the scores are simply the results of tests on an "as is" basis. If the child is wearing glasses, for example, the tests are made through the glasses, regardless of the efficiency of the glasses. T h e point is that the screening scores are simply performance-test results, and no attempt should be made to compare them with clinical-test data taken under different boundary 2

Review of Vision Screening conditions. T h e question is: can screening standards be set that will identify the children who need professional attention? T h a t is all. Individual tests within a screening battery need not correlate highly with clinical tests having similar names. Many of the reported studies on vision screening indicate, either by implication or directly, that all children can be divided into two groups, those who pass and those who fail the screening. Although this may be artifically produced in a screening, the vision measurements on any of the tests do not actually have a bimodal distribution. Each visual function is a continuous variable showing distributions of various types of skewness and kurtosis, but continuous none the less. What is attempted, in establishing the criteria of failure for a particular screening method, is the determination of dividing lines, or cut-off points, that will separate, on the basis of the test items in that battery, those who need professional attention from those who do not. Where we draw these lines will determine who will pass and who will fail, how many will pass and how many will fail. And the various criteria together will reveal the visual characteristics of those who do fail. Even with screening tests of perfect reliability and validity there is no natural dichotomy, and these dividing lines, must be determined. With the maximum amount of clinical information available on a large number of children, experts have had difficulty in agreeing on these cut-off points. Yet, ultimately, the determination of whether a child has been correctly or unnecessarily referred will be made by the ophthalmologists and optometrists in the community. And since there is a wide range of opinion among ophthalmologists and optometrists on what constitutes a vision problem, the determination that a child has been correctly referred may be decided by which particular doctor the parent consults. T h e professional people consider at least three things in analyzing a vision problem. It is not just the person's physiological problem but also his visual requirements and his sensitivity to the problem which must be considered. T a k e n together they form the basis for a clinical judgment. Because forming a clinical judgment is a complex and personal process, it is obvious that there will be differences of professional opinion, but there is a great need for a widely accepted set of standards against which screening effectiveness can be measured. No such standards 1 exist today. T h e designer of a vision-screening program must select the tests and establish the cut-off points. Since it is important that the screening be rapid, easily understood, and economical, the choice of tests to be used (from the many available) is a complex one, and compromises are necessary. These compromises involve including or leaving out certain tests. Moreover, the reliability of each test and the method as a whole must be considered. Most methods are definitely limited in the types of vision problems they can screen out and in the accuracy of the measurements. T h e teachers, nurses, or others who do the screening and the parents who receive the reports on their children should be aware of these limitations. Vision screening does more than identify certain children as being in need of professional attention. In a very real sense it implies that the child who passes the screening has no vision problem. In view of the limitations of screening and the past performance of many methods, this is far from certain. 3

Review of Vision Screening Vision-screening tests result in four classifications: correct-referrals, those who fail the screening and on professional examination are found to need vision attention; over-referrals, sometimes called "false positives," those who fail the screening and on professional examination are found not to need vision attention; underreferrals, sometimes called "false negatives," those who pass the screening but who on professional examination are found to need vision attention; and nonreferrals, those who pass the screening and who on professional examination are found not to need vision attention. Correct-referrals and non-referrals are considered screening successes; over-referrals and under-referrals are considered screening errors. In an unevaluated screening program, in which no attempt is made to find the number of under-referrals, the over-referrals assume an emphasis as screening errors and the under-referrals are not generally considered. Every screening test places some children in each of the four categories. Some screening programs have more "successes" and fewer "errors" than others, but none is perfect. T h e relative efficiency of different tests, as measured against an established set of criteria, was the subject of this investigation.

METHODS OF VISION SCREENING Many methods and techniques the vision problems of school children. representative testing methods have been been made to give detailed descriptions of is a fairly complete list.

have been used by investigators to assess Many more have been suggested. T h e selected for discussion. No attempt has all methods available, but the following

Symptoms Inventories—a series of questions designed to detect the presence or absence of symptoms indicative of vision problems. Observation—of the behavior of children in situations involving the use of the eyes. School Achievement—when it is not commensurate with mental ability, particularly in reading. Paper and Pencil Tests—which involve no content knowledge, but only visual recognition of forms. Visual Acuity—by using different sizes of figures, which the child is asked to identify, it is possible to assess the child's ability to see distinctly. Plus Sphere Test—the child looks through a pair of plus sphere lenses (+1.50 D.S. to +2.50 D.S. have been used), and if he sees the visual acuity chart clearly (20/20) he is considered to have a vision problem. Cover Test—to estimate the degree of coordination between the two eyes and may be made at distance (20 feet, or 6 meters) or near (16 inches, or 40 centimeters). Worth 4-dot Test—a bichrome test of fusion that reveals problems in the coordination of the two eyes. Maddox Rod Test—determines the postural position of the eyes when fusion is disrupted, related to coordination problems. California State Recommended Procedure (CSRP)—includes visual acuity, plus sphere test, and optional use of cover test. 4

Review of Vision Screening Massachusetts Vision Kit (MVK)—includes visual acuity, plus sphere test, and Maddox rod test at distance and near. Telebinocular—a stereoscope and series of double picture stereograms for testing, at optically projected distance and near points, visual acuity, lateral imbalance (phoria), fusion, stereopsis, and a rudimentary color test. Ortho-Rater—a stereoscope using pairs of transilluminated slides similar in construction and test content to the Telebinocular. Sight-Screener—a vision-screening battery in the Brewster stereoscope form, similar in construction and test content to the Ortho-Rater and Telebinocular. Modified Clinical Technique (MCT)—a modification of clinical procedures, including visual acuity, skiametry, cover test, and inspection for pathology or anomalies, for use in screening.

COST FACTORS IN VISION SCREENING Before we consider some of the previous studies on vision screening it is well to mention the factors that influence the cost of screening. Expense of equipment, personnel involved, and time required determine the direct costs of vision screening. If teachers do the testing, as in the California State Recommended Procedure, the time required to train the teachers and the time required to do the testing are chargeable to the screening program. T o the over-all cost of a test must be added the cost of any retesting which is done. The rapidity with which the tests can be given effectively markedly influences costs. Although the skill of the testers, and thus their speed, will affect the time required for each test, it is obvious that the number of tests will also influence the time and cost per child. Preparation of forms, scoring, and so forth should be considered in estimating costs. T h e people who can be called upon to do vision screening have different degrees of skill and draw different hourly rates of pay, both of which will influence the time and cost per child screened. Teachers, school nurses, technicians, optometrists, and ophthalmologists have been employed for the various screening methods. It is obvious that the cost of the screening must be compared to the efficiency of the screening. A method that results in many over-referrals will cost the community in unnecessary examination fees. A method that under-refers ignores the long-range consequences of not identifying the child who needs professional attention.

BRIEF REVIEW OF SELECTED STUDIES Reports on vision screening of elementary-school children indicate that previous vision studies can be classified into three general types. T h e most common, until recent years, was the vision study which reported the presence of certain vision problems in the school population as identified by a particular screening method. T h e report of this kind of study was largely incidental to the effort of finding the children with vision problems, to the investigation of the vision characteristics of school children, or to the study of the relation of vision problems to reading achievement. Little attempt was made to evaluate the screening method used. 5

Review of Vision Screening W i t h the development of a variety of screening methods, researchers began to compare their results against clinical results obtained by optometrists and ophthalmologists, u p o n whom the ultimate responsibility for professional care of the referrals depended. In most of these screening studies, the clinical criteria were based on the j u d g m e n t of one or more optometrists or ophthalmologists. In some screening studies the bases for these criteria are not given in the reports. I n very few screening programs was any attempt made to evaluate these criteria, and in fewer still was any attempt made to bring both professions together on this matter. I n some of these studies, a screening method was rated on how many of its referrals were correct and how many were unnecessary. I n others, the effectiveness of several methods was compared. T h e reports of these studies reveal an overemphasis on the over-referrals as screening errors and a lack of emphasis on the under-referrals. T h e third group of studies involved the clinical testing of the entire population under study, or a representative sample and all referrals, to determine those children in need of professional attention. Again, somewhat arbitrary standards were used. T h e effectiveness of various screening methods was measured against clinical j u d g m e n t or criteria. T h u s the screening methods were evaluated in terms of their correct-referrals, their over-referrals, and their under-referrals. Since both over-referrals and under-referrals are screening errors, this latter type of study is more valid in assessing the effectiveness of vision screening. Since it would not contribute to o u r purpose to review a l i o f the many studies reported in the literature, we have selected for review studies which are representative. Moreover, no attempt was made to analyze completely any one study in this field. For references to the following studies, studies not cited, and other material pertinent to this study, see the bibliography. St. Louis Study T h e St. Louis Study (1952), by Crane, Scobee, Green, and Price, was a major attempt to evaluate the effectiveness of vision screening at two grade levels. A comparison was made of the screening scores and an ophthalmologist's clinical data on 606 first graders and 609 sixth graders. A wide variety of screening methods was used with trained persons doing the testing. T h e n u m b e r of children w h o were wearing glasses or were u n d e r treatment is not given in any of the published reports. T h e r e is much valuable information in the main report on the relative effectiveness of different screening methods. T h e reports indicate that the better the training of the tester the more efficient the screening. T h e three stereoscopic devices used in the study—the Ortho-Rater, the Sight-Screener, and the Telebinocular-—gave very similar results. Although, for each device, the n u m b e r of correct-referrals was high, the over-referrals exceeded the n u m b e r of correct-referrals. T h e Massachusetts Vision Kit (MVK), Snellen visual acuity at distance and near, Teacher Judgment, and different combinations of these tests were also used. T h e efficiency of these tests varied from a () coefficient of 0.45 average for the MVK and Snellen tests to a low of 2 1 1 n 1 0 1 2 2 11157 4 9 4| 1 56 0 3 ¡1 2 8 2 9 5 5 4 2 3 2 5 3 î 1 56 1 1 2 1 3? 0 1 2 # I TOTAL PB3RA 3 12 8 29 5 5 52 3 2 53 î 1 57 TOTAL TROPU ÌRIS* DO IPTERSis 15U131211109 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10u 12131415Ì5

NEAR (40crrO AT DISTANCE (6 M 1 1 ROPIA [ PHORIA 1 PHORIA 1 TROPIA nyper j hyper hyper | hyper

QUESTIONABLE REFERRALS

UNNECESSARY REFERRALS

TOTAL TROPU TOTAL PH0R1A

PROBLEMS

TOTAL TROPU103 1 1 2 3 2 1 1 4 7 1 ? 1 6 1662 1 1 TOTAL PH3RA I1 2 3 3 1711« 10U 6 4 4 2 1 2 1 1 1 1 127 1 2 1 3 12 & 41 < 211 2 1 öl 8 S 051112 2 1 1 4 7 1 2 1 6 1348 8A

6

0

6

1

e

0

0

1

1 0

0

0

0

2

0

2

0

3

1

0

0

3

Questionable-referrals Failed near esophoria only* Failed other coordination only Failed coordination and one other criterion

S

0

0

1

0

0

0

0

0

2

0

0

1 0 0 0 0

0

0 0 0

0 0 0 0

1 0 0 0

0

2

2

0 0 0

1 0 1

16 2

1

6 6 1

5 2 0 3

Near exophoria of Referrals 8»

Failed Failed Failed Failed Failed

Correct-referrals near esophoria onlyt other coordination only coordination and one other criterion coordination and two other criteria coordination and three other criteria....

Questionable-referrals Failed near exophoria only f

Total

9*

10*

il*

124

131

>I3A

0

2

1

g

s

5

0 0 0 0 0

s

3

1 0 0 1 0

1 0 0 0 0

0 0 1 1 0

1

1 0 0 0

0

0

0

0

0

0

0

0

1 1 1 0

12 4 2 2 2

2

2

0

3

0

3

* "Near esophoria only" means esophoria at the near point with 4A or less esophoria or exophoria at distance, or less hyperphoria at distance and near, no tropia. t "Near exophoria only" means exophoria at the near point with 4A or less esophoria or exophoria at distance, 1A or less hyperphoria at distance and near, no tropia.

complete clinical examination of the student's visual system as a whole, not on the results of individual tests. The student's visual health and welfare as well as his visual performance were considered in making a decision. This analysis by individual-test results is useful when it successfully describes these decisions in terms complete routine that are more easily applied than the results of complicated and professional judgment. This is in no way to be considered a examination substitute for the clinical examination and professional judgment. Thus the reader should be aware of the limitations of such analyses as are included here. It should not be inferred that the optometrists and ophthalmologists engaged in this study feel that all students whose vision data fail to meet the proposed criteria (correctreferrals) should have treatment. Nor should it be inferred that any student whose vision data meet the proposed criteria (unnecessary-referral) should have no treatment. These criteria are simply a minimum description of the professional decisions and serve as guide lines for screening referrals, criteria against which screening effectiveness can be measured. Those who fail the criteria should at least be examined by an optometrist or ophthalmologist. A few students may pass the

30

Need for Vision Attention TABLE

6

DETERMINATION OF CLINICAL CRITERIA FOR REFERRAL, 1 9 5 4 : ORGANIC PROBLEMS (N = Condition

Lids Marginal blepharitis Papilloma (suspected) Resolving hordeolum Inflamed puncta (scratch) Trichiasis (skin graft) Anterior Segment Conjunctivitis (poison oak) Corneal opacity Possible iris lesion Lens

1,163) Require treatment

Require observation

Anomaly noted

26

21

3

2

21 2

21

Total

1

1

1

1

1

0

2

1

2

1

S 3

Vitreous Signs of old penetrating injury

1

Retina and Choroid Drusen-like spots in retina Old chorioretinitis

2

1

0 0

1

2

1

2

0

1

1

1

0

2

1

1

1

1

36

2

1

2

Opacity

Total

2

1

21

8

0

7

criteria who need professional attention, but the parents and others, by close observation and awareness of symptoms, are the only ones who can become aware of these situations. T h e fourth characteristic considered part of the clinical referral criteria, organic problems, was not subjected to the same type of analysis as the other three. It was agreed by the members of the study staff that any student with a verified pathology or medical anomaly of the eye or adnexa would be classed as a correctreferral. It was agreed that this criterion, not subject to minimum and maximum limits, would be the same throughout the study. T h e organic problems encountered are described in table 6.

RECLASSIFICATION OF QUESTIONABLE-REFERRALS Since the clinical referral criteria adequately describe the clinical decisions and separate the correct-referrals and the unnecessary-referrals, it was decided to apply these to the questionable-referrals and reclassify them into either the "correct" or "unnecessary" category. This was done to simplify subsequent analyses of the screening methods. It will be noted that although the choice of minimum or maximum limits for the referral criteria does not affect the correct-referrals or the unnecessary-referrals, it does have a definite influence on the reclassification of the questionable-referrals. If the minimum limits are used, the 57 questionable31

Need for Vision Attention referrals will be reclassified as 33 correct-referrals and 24 unnecessary-referrals. If the m a x i m u m limits are used, the 57 questionable-referrals will be reclassified as 29 correct-referrals and 28 unnecessary-referrals. After careful consideration of the various comparisons presented, the study staff decided to use the m a x i m u m limits for establishing the clinical referral criteria. These are listed in table 7 and shown as heavy black lines in figures 1-3.

INTERPROFESSIONAL VISION-SCREENING QUESTIONNAIRE Recognizing that the above analysis, elaborate though it is, is only a description of the opinions of the four persons involved, the study staff decided to investigate by questionnaire the opinion of a representative n u m b e r of pracTABLE

7

CLINICAL CRITERIA FOR REFERRAL Characteristic measured

Visual acuity Refractive error Hyperopia Myopia Astigmatism Anisometropia Coordination At distance (20 feet) Tropia Esophoria Exophoria Hyperphoria At near (16 inches) Tropia Esophoria Exophoria Hyperphoria

Criteria of correct-referral

20/40 or less, either eye + 1.50 -0.50 ±1.00 ±1.00

D.S. or more D.S. or more D.C. or more D. or more

Any 5A or more 5A or more 2 4 or more Any 6 4 or more 10A or more 2A or more Any verified pathology or medical anomaly of eye and/or adnexa

ticing ophthalmologists and optometrists concerning these criteria. T h i s supplementary study is presented in chapter vin. T h e replies of 279 optometrists and 261 ophthalmologists are compared with the study criteria in table 8. T h e information from the questionnaires is treated by means of the inter-quartile range and the median (Q 2 ) is taken as the measure of central tendency. T h i s method of analysis is used to reduce the effect of extreme answers at each end of the distributions and because of the lack of normal distributions. T h e Q, indicates that at least 25 per cent of those reporting gave values at this measure or less; Q , indicates the median value; Q 3 indicates that 75 per cent of those reporting gave values at this measure or less. T h e range from to Q 3 includes at least the middle 50 per cent of the answers in each distribution. T h e agreement between the Orinda Vision Study criteria and the replies f r o m the questionnaire is quite close, considering the difference in the approaches used. 32

N e e d for Vision Attention T A B L E

8

CLINICAL C R I T E R I A COMPARED WITH C R I T E R I A IN I N T E R P R O F E S S I O N A L S C R E E N I N G Q U E S T I O N N A I R E Correct-referrals Characteristics measured

Visual acuity Refractive error Hyperopia Myopia Astigmatism Anisometropia Coordination At distance Tropia Esophoria Exophoria Hyperphoria At near Tropia Esophoria Exophoria Hyperphoria Organic problems

Clinical criteria

Questionnaire

Q.

Q*

Qa

20/40

20/30

20/30

20/40

+ 1.50 -0.50 ±1.00 ±1.00

+ 1.00 -0.50 ±0.50 ±0.75

+ 1.50 -0.50 ±0.75 ±1.00

+2.00 -0.75 ±1.00 ±1.50

Any 5A 5* 2A

Any 3A 3*

Any

Any 6*

Any 6A 10A 2* Any

Any 2*

Any

8*

1* Any

4A

5A 1Ä

44

10A 1* Any

8*

2A Any 7

A

12* 2A Any

This comparison, however, does not show the extreme ranges of answers received. The wide variations between members of each profession and between the two professions indicate the real need for further research and education regarding this problem. It is obviously impossible to reduce over-referrals and under-referrals to a minimum by even a "perfect" screening method unless the eye practitioners in the community are in better agreement on what constitutes a correct-referral. It is hoped that the analysis presented in this section will provide this muchneeded definition.

DISTRIBUTION OF CRITERIA FAILED Having established the criteria that describe the clinical decisions for referral, we now had to describe the visual characteristics of the group in terms of these criteria. Figure 4 shows this distribution in two ways. The graphical part shows the correct-referrals distributed by criteria failed. The area of each pie-graph is proportional to the number failing that criterion. Thus the greatest number failed the refractive error criterion, and the smallest number failed the organic criterion. But the children labeled correct-referrals frequently failed more than one criterion. Thus, in 1954, of those who failed refractive error, 33 per cent failed this criterion only, 47 per cent failed this criterion plus one other, 18 per cent failed this criterion plus two others, and 2 per cent failed all criteria. It is interesting to note that of the four criteria used, the one that could be eliminated and miss the least number of correct-referrals is visual acuity. This is true because 33

FIGURE

CLINICAL

4

VISUAL A C U I T Y

CRITERIA

FAILED - CORRECT

REFERRALS

VISUAL ACUITY

VISUAL ACUITY

REFRACTIVE ERROR

REFRACTIVE

COORDINATION

COORDINATION

COORDINATION

ORGANIC

ORGANIC

ORGANIC

PKHCETT FAHZD 1913 CRTTgRIOH OHLT PKRCEtT FAIZO) THIS CRITBUOH PUB OHE OTHB m c m r r u L m this CRITERION FLOS TDD OTHBtS istcorr r u L m ALL

TORN CRITERIA

N=95 REFRACTIVE

ERROR

ERROR

COMBINATIONS OP CLINICAL CRITERIA ?AI7£D - CORRECT R5FURALS Totel 1 5 - 7 Total Failed One Criterion Only Visual Acuity Refractive Error Coordination Organic Failed Two Criteria Visual Acuity and Refractive Error Refractive Error and Coordination Visual Acuity and Coordination Coordination and Organic Refractive Error and Organic Visual Acuity and Organic Palled Three Criteria Visual Acuity,Refractive Error,Coord. Visual Acuity, Refraotive Error,Organic Visual Acuity,Coordination,Organic Refractive Error.Coortinatlon,Organic Failed Four Criteria Vis. Acuity, Refract.Error, Coord., Organic

195< I 8 - 1C III - 13

1956 Total I 7 - 9 11C - 12 113 - 15

Need f o r Vision Attention

most of those failing visual acuity also failed other criteria; it is, therefore, the least independent of the criteria. T h e table part of figure 4 shows the distribution arranged in a different manner—by the number and groups of criteria failed by age grouping as well as totals. In terms of the criteria established, this shows the visual characteristics of the correct-referrals and shows that the most frequently failed combination of criteria is visual acuity and refractive error. If all correct-referrals failed all four criteria, then any one of the criteria would be sufficient in screening. Since about half of them failed only one criterion, and some of these failed each one, all four are necessary.

RELATION BETWEEN VISUAL ACUITY AND REFRACTIVE ERROR Since the most frequently failed criteria are visual acuity and refractive error, it may be assumed that there is a close relationship between these two. Many studies that recommend visual acuity testing as a means of vision screening assume that this is so. A supplementary study was done on this relationship and is presented in chapter vm. This study shows the relation between the uncorrected visual acuity and the refractive error of 1,920 eyes of children between the ages of 6 and 13 years. T h e records of children examined in the Orinda Vision Study were utilized and, to obtain an adequate sample of higher refractive errors, records of children admitted to the refracting clinic of the University of California School of Optometry were included. Only records of eyes that were free from pathology, amblyopia, or medical anomalies that might affect visual acuity were used. T h e relationship is demonstrated to be far from simple, and visual acuity cannot reasonably be expected to predict refractive error, though the reverse is true in the absence of pathology, amblyopia, or medical anomalies. Those failing only the visual acuity test by the study standards were children with borderline myopia, myopic astigmatism, or amblyopia, and there were relatively few of them in the population studied.

SUMMARY T h e clinical criteria have been established by analyses of the clinical examinations and the decisions of the ophthalmologists and optometrists of the study staff. This analysis indicates that four criteria, and only four, are needed, with appropriate cut-off points, to describe the clinical decisions and to separate the correct-referrals from the unnecessary-referrals. These criteria are visual acuity, refractive error, coordination, and organic. T h e cut-off points on each of these criteria were the same for each age group. T h e distribution of criteria failed by the correct-referrals is given by age group, number, and combinations failed and number failing each criterion for each year 1954-1956. T h e efficiency of the various screening methods is evaluated in relation to the decisions based on complete clinical examinations. T h e decisions were made on the need for professional attention—rather than treatment or care. T h e clinical criteria derived in this section describe the clinical decisions in 1954, and were applied without modification in 1955 and 1956. 35

IV

Effectiveness of Vision-Screening Methods

T h e many factors that can influence the effectiveness of vision screening may be roughly divided into three groups. T h e first group, concerned with the method itself, includes the number and variety of tests in the battery, the coverage of the major problems of vision, the mechanical arrangement of the equipment, the way a test is given, the reliability and validity of the tests, and, most important, the ability of the tests to give measurements that can be used in selecting those children who should have further attention. In this study the primary emphasis is on the results of each method as a whole rather than by part tests. Part-test information is included in appendix A. T h e factors in the second group are those associated with the tester. These are the interest and personal ability of the tester, his background information, his training and experience with particular equipment, his familiarity with the problems of vision screening, and his attitude toward the problems. T h e third group of factors, concerned with the children being screened, include age, previous screening experience, socioeconomic status, and type and amount of previous professional attention. RESULTS, 1954 T h e screening methods used in 1954 are described in chapter n. Those children referred by each screening method were given clinical examinations, if these could be arranged. There were two exceptions: both Teacher Observation and the Massachusetts Vision Kit (MVK) resulted in large numbers of referrals, all of whom were not given clinical examinations. T h e results with these two methods were studied on the control group, since clinical examinations for those in this group were available. T h e proportion of over-referrals was found to be particularly high. With Teacher Observation, children referred because of "strains to see" and "tilts head," when unaccompanied by failure of any of the vision performance tests, were usually found to be over-referrals. With the MVK, the failures on the lateral phoria test, unaccompanied by failure on other tests, were usually found to be over-referrals. T h e evaluation of these as over-referrals without clinical examination was consistent with the predicted results from the study of 36

Effectiveness of Screening Methods TABLE 9 COMPARISON OF CONTROL AND NONCONTROL GROUPS, 1954 Basis of comparison

Number Sex (Male)

Control 221

Per cent 100

Noncontrol

Per cent

Total

Per cent

114

51.6

942 502

100 53.2

1,163 616

100 52.9

By Teacher Observation Correct Unnecessary

52

23.5

229

24-3

278

23.8

13 39

5.9 17.6

65 164

6.9 17.4

75 203

17.4

By Nurse Observation Correct Unnecessary

11

5.0

69

6.1

2.7

48

6.1

6

24

2.1

5

2.3

30

1.9 3.2

35

3.0

By State Recommended Procedure Correct Unnecessary

30

13.6 7.2

144

16.3

16 14

79

8.4

6.3

65

6.9

79

8.2 6.8

By Massachusetts Vision Kit Correct Unnecessary

98

44-3

417

44-S

516

44-3

29

128 289

13.6

157

69

13.1 31.2

30.7

358

13.5 30.8

By Modified Clinical Technique Correct Unnecessary

48

21.7

198

20.9

246

21.2

41

18.5 3.2

168 30

17.7 3.2

209

18.0 3.2

Referrals

7

18

m

95

37

6.4

15.0

the control group. It was felt that the additional time and effort necessary to obtain clinical examinations for these children would not materially alter the results. T h e results with this procedure for the control and noncontrol children are compared in table 9. Further study of the accuracy of these predictions was made from the tests on the same students in 1955 and 1956 and justifies this procedure. In the control group were three children who, because of their vision characteristics, should have been correct-referrals, but who were not referred by any of the screening methods. One was in the age group 8-9-10, and two were in the age group 11-12-13. Since all children were not given clinical examinations, the total number of undetected correct-referrals in the population was estimated on the basis of the number of unidentified correct-referrals in the control group. Thus the three correct-referrals unidentified by any screening method in the control group indicate, on the basis of the size of the age group from which the control sample was taken, fourteen undetected correct-referrals in the total population: six in the 8 - 9 - 1 0 age group and eight in the 11-12-13 age group. These estimated correct-referrals were added to the total known correct-referral for statistical evaluation, and thus constitute part of the under-referrals for each visionscreening method. This distribution is shown in table 10. T h e results of each screening method can be described in terms of the number

37

Effectiveness of Screening Methods

of children it identifies correctly and the number it identifies incorrectly. Screening successes are the correct-referrals and non-referrals, and screening errors are over-referrals and under-referrals. T h e total number in each classification for each of the screening methods is shown in table 11. T h e results of the screening methods, with the exception of the Parent Questionnaire, are shown in figures 5a and 5b. T h e graphs show the percentage of the total group classified for each method. T h e relative efficiency of each method can be compared directly. For some of the methods the advantages of a greater number of correct-referrals must be weighed against the disadvantages of a greater number of over-referrals. TABLE

10

CLINICAL STUDY OF CONTROL GROUP TO-IDENTIFY UNDER-REFERRALS, 1954 Age Children

Total 8-9-10

Total in population

11-12-13

1,163

349

458

Total in control group (clinical) Correct-referrals Non-referrals

221

SI

78

92

47 174

7 44

12 66

28 64

Referred by screening of control group Correct-referrals Unnecessary-referrals

122

40

41

41

44

7

11

78

33

30

26 15

3

0

1

2

14

0

6

8

Unidentified referrals in control group Correct-referrals Projected unidentified referrals in total population Correct-referrals

356

Figures 5a and 5b give the actual number in each referral classification by age group as well as by total. T h e second column of the tabulations gives the percentage of the total for each group. T h e third column gives the per cent of criterion—a comparison of the number in each classification against the number that should be in each classification. T h u s the true number of correct-referrals becomes 100 per cent, and the per cent of the "correct-referrals" and the per cent of the "under-referrals" identified by each method are given. Similarly the true number of non-referrals becomes 100 per cent, and the per cent of the "nonreferrals" so classified and the per cent of "non-referrals" unnecessarily referred by each method are given. T h e fourth column contains the correlation coefficients used in this study. T h e phi coefficient is most representative, but the tetrachoric correlation coefficient is also given for each age group and the total on each screening method. T h e fifth column, based on relative numbers, predicts the number of referrals for each method. T h e number of correct-referrals, over-referrals, and 38

Effectiveness of Screening Methods under-referrals that would result from each 100 referrals for each screening method is given. T h e Parent Questionnaire, not included in the figures 5a and 5b, contained eighteen questions to be answered yes or no. T h e questions involved symptoms of visual discomfort, observable visual behavior, problems in visual performance, and so forth, that parents might be expected to note. If one or more yes answers T A B L E 11 SCREENING RESULTS BY REFERRAL CLASSIFICATION, 1954 ( N = 1,163) Correctreferrals

Method

Clinical Criteria Parent Questionnaire Teacher Observation Nurse Observation State Recommended Procedure Massachusetts Vision Kit Modified Clinical Technique

231 88 75 24 95 157 209

TJnderreferrala

Overreferrals

Nonreferrals

0

0

932

143 156

215 203

717

207 136 74 22

35

729 897

79 358

853 574

37

895

can be considered cause for referral, there were 88 correct-referrals and 215 overferrals. T h e phi coefficient is +0.14 with an associated chi-square significant beyond the 1 per cent level. An item-by-item breakdown, however, showed that most of the questions h a d little or no significance. Question 12, concerning crossed or deviated eyes, contributed almost all the value of the chi-square. T h i s reveals that the parent seldom makes an over-referral error when he indicates that his child's eyes deviate. However, it is interesting to note that, although there were actually 62 children in the sample who had deviated eyes, only 16 parents reported it. Careful study of the responses to the individual questions resulted in the development of the questionnaire used in 1956. These questionnaires are included in a p p e n d i x c. T h e methods are ranked in order of efficiency as follows: Ranking of efficiency 1 2 3 4 5 6

Method

Modified Clinical Technique California State Recommended Procedure Massachusetts Vision Kit Parent Questionnaire Nurse Observation Teacher Observations

« 0.85 0.37 0.24

Tt

0.97 0.60 0.37

0.14 0.12

not valid

0.28

0.10

0.23

T h e Modified Clinical T e c h n i q u e was considerably more efficient than the next best method. It referred the greatest n u m b e r of correct-referrals (90 per cent) a n d the fewest over-referrals (4 per cent). T h e second-best method, the CSRP, identified less than half of those needing attention though it referred only 8 per cent of those who did not need attention (over-referrals). T h e MVK had a high over39

FIGURE

CLINICAL

EFFECTIVENESS OF SCREENING

5a

CLINICAL CRITERIA TOTAL

CRITERIA

D

"

Correct-Referrals Over-Referrals NOT REFERRED Unde I—Re ferra Is Non-Referrals AGE GROUP 5-6-7 Correct-Referrals Over-Re ferraIs NOT REFERRED Under-RaferraIs Non-Referrals ftGEj QROUP 3-9-10 Correct-Referrals Over-Referrals NOT REFERRED Under-ReferraIs Non-Referrals AGE GROUP 11-12-11 REFERRED Correct-Referrals Over-Referrals NOT REFERRED Under-ReferraIs Non-Referrals

TEACHER OBSERVATION

TEACHER OBSERVATION TOTAL

Correct-ReferraIs Over-Referrals NOT REFERRED Under-Referrala Non-Referrals AGE GROUP 5-6-7 REFERRED Correct-Re ferrala Over-Referrals NOT REFERRED Und er-Referra I s Non-Referrals

Number 1163

221

*Tot«l 100

22

¡(Critei« Cor.Coe^

20

100

100

55

80 100 ìé 16

224

k

231

m 932 349

55

29*

2Z 97

356

22 79

21

100

100

277

à

277

78

100

Number II63

ÎTotal 100

Writer

278 75

2L

m

26 13 _61

203 156

729

t

(ÏÎOO)

(1.00) rt (1Î00)

_22_ 100 22

r

(1.00)

(1.00) 100

22

t

(1.00)

*

84 100

21

1954

(1.00) rt (1:00)

7 17

AGE GROUP 8 - 9 - 1 0

Correct-Referrals Over-Referrals NOT REFERRED Under-Referrala

Correct-Referrals Over-Re f e r r a I s NOT REFERRED Under-Referrals Non-Referrals

NURSE OBSERVATION

NURSE OBSERVATION TOTAL REFERRED

Correct Referrals Over-Referrals NOT REFERRED Under-Re ferraIs Non-Referrals

AGE GROUP 5 - 6 - 7

Nuniber II63 52 24 35 1104 207 897

»Total 100 5 2 3

*Criter 1

18 77

Correct-Referrals Over-Referrals NOT REFERRED Under-ReferraIs Non-Reforrala Correct-Referrals Over-Referra1s NOT REFERRED Under-Re ferraIs

Correct-Referrals Over-Re ferra1s NOT REFERRED

KET: • M R CORRECT REFERRALS t-:-: : : :'] ÜNDÖI-REFERRALS ninnili OVEt-REFERRALS I 1 NON-REFERRALS

Footnotes - Figures 5a and 5b a

. Graphical presentation l a "per cent of t o t a l " for the whola group tested.

b . See text for methods used to determine c r i t e r i a . c . Figures shown In whole percentage units to f a c i l i t a t e Inspection of scatters and "forced" to make each t o t a l 100.

FIGURE

STATE

EFFECTIVENESS OF SCREENING

5b

RECOMMENDED

PROCEDURE

STATE RECOMMENDED PROCED TOTAL REFERRED Correct-Referrala Over-Referrals NOT REFERRED Under-Referrala

Number 1163

m

95 79

iCTotttl 100 IS

8

ÌCritei

7

41 8

12

59

25

1954

Correct-Referrals Over-Referrals NOT REFERRED Under-Referrals Non-Referrals AGE GROUP 8-9-10 REFERRED Correct-Referrals Over-Referrala NOT REFERRED Under-Referrals Non-Referrals APE GROUP 11-12-13 REFERRED Correct-Referrals Over-Referrals NOT REFERRED Under-Referrals Non-Referrals

MODIFIED CLINICAL TECHNIQUE

MASSACHUSETTS VISION KIT TOTAL REFERRED Correct-Referrals Over-Referrals NOT REFERRED Under-Referrals Non-Referrala AGE GROUP 5-6-7 REFERRED Correct-Referrala Over-Referrala NOT REFERRED Under-Referrals Non-Referrala AGE GROUP 8-9-10 REFERRED Correct-Referrals Over-Referrala NOT REFERRED Under-Referrals Non-Referrals AGE GROUP 11-12-13 REFERRED Correct-Referrals Over-Referrals NOT REFERRED Under-Referrals Non-Referrals

Number 1163

MODIFIED CLINICAL TECH. TOTAL REFERRED Correct-Referrala Over-Referrals NOT REFERRED Under-Referrals Non-Referrals AGE GRODP 5-6-7 REFERRED Correct-Referrals Over-Referrals ]JOT REFERRED Under-Referrals Won-Referrala p APE GROUP 8-9-10 REFERRED Correct-Referrals Over-Referrala NOT REFERRED Uwier-Ref erra I a Non-Referrals ACE GROUP 11-12-11 REFERRED Correct-Referrala Over-Referrals DOT REFERRED Under-Referrals Non-Referrals

Number 1163 216 209 37 917 22 895

515 157 358 648 7A

¿58 203 69 134 255 28 227 356 Vn 57 122 XÜ. 22 155

d . See t e x t f o r discussion of s t a t i s t i c a l methods employed: phi c o e f f i c i e n t (#); and tetrechorlc c o r r e l a t i o n ( r t ) . e . See t e x t f o r discussion of proportional method employed: P • predicted r e s u l t s per 100 r e f e r r e l e . f * A l l 0 c o e f f i c i e n t s have associated ohi-squares which are s i g n i f i c a n t beyond the ljI l e v e l except those marked ( f ) . ( . Tetraohorlc correlations not v a l i d because of small number of r e f e r r a l s , h. Lea* than 0 . 5 Î .

¡«Total JtCriter Cor.Coel 100 U. 11 13 31 0.2A

5&

T t 0.37

100 50 16 % 50 hU JCCriter

Effectiveness of Screening Methods referral rate: almost three-fourths of those referred did not need attention. Observation must be concluded to be an ineffective method of identifying those in need of visual attention. Teachers, nurses, and parents all gave observations that were unsatisfactory. It has been suggested that Teacher Observation combined with teacher testing of visual acuity would yield satisfactory results. Although this was not used as a specific technique, teachers did test visual acuity as part of the CSRP, and thus the results with this method are available. Teacher Observation by itself gives = +0.12. T h e teacher visual acuity measurements from the CSRP give $ — +0.48. TABLE

12

EVALUATION OF SCREENING REFERRALS, 1 9 5 5 Children previously tested, 1954

Children new to s t u d y , 1955

Total

Correct-referrals Optometrists and ophthalmologists Optometrists only Ophthalmologists only Private-care reports Other Orinda Study information

179

70

249

48 55 1 12 63

28 26

76 81 1 28 63

Unnecessary-referrals Optometrists and ophthalmologists Optometrists only Ophthalmologists only Private-care reports Other Orinda Study information

584

280

864

10 48

1 13

11 61

3 523

1 265

4 788*

Clinical examinations b y

16

* Includes 737 referred b y Telebinocular only.

In combining these two, if each child is referred who fails either observation or visual acuity or both, then = +0.28. A n d if only those children are referred who fail both observation and visual acuity, r\ t-- 8 •(T N tf\ r-i CV m S 3 3 H fe É5

5 C

o H

Í3

.û B< u-t3 £ S f® ® öù ^ i* -e o CO -h co H tu o V H ¡> Eh

M 'S 03 '3.. Q. £ K o. ® • 0) M) ^a> 'S a ö . H -t^ p en —i en v o m H >H

M e H « P g o H

a) te tí .S •S « o o > H

o Eh

«.. ¿"O-O-O SJ3 © ® S-5 S 3 3 oHwfQffl OÄ oU

Costs of Screening two tests suggest that each child failed on the first test be reexamined on that test before being referred. It was decided to evaluate this retesting method, and in 1956 all children were given the Telebinocular and MVK tests twice. Reports of this are contained in appendix A. But in arriving at the time chargeable to the testing by these methods, the entire first-test time and that part of the secondtest time spent retesting those who failed the first test were charged against these methods. T h u s the time for the Telebinocular and MVK tests in 1956 represents the time that would normally be spent in using these methods according to the manufacturers' instructions. T h e Modified Clinical T e c h n i q u e required time for the training of the volunteer recorders, but not the testers because the optometrists were familiar with the component tests of this method from clinical practice. T w o optometrists worked at the same time each year. T w o testing lines were operating simultaneously, which allowed for the completion of this screening method in a brief over-all period, b u t did not alter the total amount of testing time nor change the time per child for this method. T h e same two optometrists were used in 1954 and 1955, b u t two others were used in 1956. T h e average hourly cost for teachers, nurses, and the psychologist who performed the CSRP, the Telebinocular, and the MVK tests was $3.50 per hour. T h e optometrists were paid $6.00 per hour, which is the regular rate of pay for part-time professional personnel in the Contra Costa County Health Department. T h e testing time for each method was multiplied by the average hourly cost for the personnel involved to arrive at the total cost of each screening. T h i s total was divided by the n u m b e r of children tested to obtain the cost per child for each method. T h e results are shown in table 26. N o estimate is given for the time and cost of Teacher Observation or Nurse Observation, and no charge was included for equipment. E q u i p m e n t would be expected to be used for some years, and its amortized cost would scarcely affect the cost per pupil. Finally, no charge was included for follow-up. It would be expected that the nurse would spend some time sending notices and talking to parents, concerning the vision program regardless of which method is used. T h i s was not estimated, b u t follow-up costs are obviously related to the total n u m b e r referred and the efficiency of the screening. T h e most typical costs were those in 1956, when the least expensive test was the MVK at 37 cents per pupil, and time of testing (including retests) averaged 6.4 minutes per child. T h e next method in order of cost, was the Telebinocular, at 43 cents per pupil, and testing time (including retests) averaged 7.3 minutes per child. T h e third method, in order of cost, was the M C T at 45 cents per pupil, and testing time 4.5 minutes per child. T h e most expensive technique was the CSRP, even when no training time was involved and the cover test eliminated. It cost 53 cents per pupil and had a testing time (including retests) of 9.2 minutes per child.

COMMUNITY COSTS T h e correct-referrals can be regarded as a necessary community cost; that is, cost to parents or community health resources to provide needed profes91

Costs of Screening

sional vision attention. T h e over-referrals, however, represent an unnecessary cost to the community. When the over-referrals (unnecessary-referrals) consult private professional services, an unnecessary expense is incurred. Each technique provided some over-referrals. In table 27, for purposes of comparison, it is assumed that the average cost of private consultations is $15.00. T h e total cost of what these unnecessary consultations would be was computed for 1956. Included in this table is the number of under-referrals to show the number of children with vision problems missed by the screening method. T h e cost of the under-referrals cannot be calculated, but their number indicates the efficiency of the method in finding those with vision problems. In the other column under under-referrals is the per cent of those with vision problems missed by the screening method. T A B L E 27 PROJECTED COMMUNITY COSTS OF OVER-REFERRALS, 1956 Over-referrals

Under-referrals

Method Number

Teacher Observation Nurse Observation State Recommended Procedure Massachusetts Vision Kit Telebinocular Modified Clinical Technique

218 4 10 33 67 14

Rate*

Cost

$15.00

=

15.00 15.00

= =

$3,270.00 60.00 150.00

15.00 15.00

= =

495.00 1,005.00

15.00

=

210.00

Number

Per cent

115 174

52

166 91 89 4

79 75 45 44 2

* Assumed to be $15.00 per professional examination.

For 1956 the greatest over-referral cost would be for the Teacher Observation: 218 over-referrals at an unnecessary community cost of $3,270.00, and 52 per cent of those needing attention were missed. T h e next greatest over-referral cost would be from the Telebinocular: 67 over-referrals at an unnecessary community cost of $1,005.00, and 44 per cent of those needing attention were missed. T h i r d would be the MVK: 33 over-referrals at an unnecessary community cost of $495.00, and 45 per cent of those needing attention were missed. For each of the preceding methods, the unnecessary community expense of the over-referrals would have been greater than the cost of screening all the children. T h e fourth, the M C T , with 14 over-referrals, would have resulted in an unnecessary community cost of $210.00, and it missed only 2 per cent of those needing attention. T h e CSRP had only 10 over-referrals, which would have resulted in an unnecessary community cost of $150.00, but it missed 75 per cent of those needing attention. T h e Nurse Observation had the fewest over-referrals, only 4, which would have resulted in an unnecessary community cost of only $60.00, but it missed 79 per cent of those with vision problems. T h e cost per correct-referral for 1956 was obtained by dividing the direct screening costs by the number of correct-referrals for each screening method. This resulted in a cost per correct-referral of $12.90 for the CSRP, $5.02 for the MVK, $4.34 for the Telebinocular, and $2.67 for the M C T in 1956. 92

Costs of Screening

I n terms of the objective of this study—to determine the screening method that finds essentially all those children needing professional vision attention with a minimum of needless referrals—the Modified Clinical Technique must be selected. Even at the higher salary rates paid, this method did not cost significantly more than the less efficient methods. When considered in terms of community costs and in terms of cost per correct-referral, it is clearly the most economical.

93

Vili

Supplemento ry Studies

Two supplementary studies were done to explore further the problems of vision screening in elementary schools. One of these was based on an interprofessional questionnaire on vision-screening criteria. T h e principal reason for using this was to ascertain the degree of agreement between the clinical criteria of this study and the opinion of representative optometrists and ophthalmologists in the nation. Since children referred by any vision-screening program will usually be seen by optometrists and ophthalmologists in their community, the majority opinion, and the variability of this opinion, on what constitutes a correct-referral was considered to be of importance. A child referred by a screening program may be considered an over-referral by one practitioner and a correct-referral by another. A child classified as normal by the criteria of a screening program may be considered to be in need of attention (under-referral) by some practitioners. These differences in professional opinion have a definite bearing on the effectiveness of a vision-screening program and its acceptance in the community. T h e second supplementary study was done to explore the relationship between visual acuity and refractive error in the age range from 6 to 13. I n many methods used for the vision screening of elementary-school children there is an assumed or implied relationship between visual acuity and refractive error. At least it is assumed that significant refractive errors will affect visual acuity. Most of the studies of this relationship have relied on a method of averaging the two principal meridians of each eye to obtain a measure of the refractive error known as the "equivalent sphere." Since this method effectively masks the influence of astigmatism, the scope of the relationship, we felt, had not been adequately explored.

INTERPROFESSIONAL QUESTIONNAIRE ON VISION-SCREENING CRITERIA From the middle of February to the first of March, 1956, identical questionnaires were sent to 630 optometrists of the American Academy of Optometry and to 500 ophthalmologists, 260 members of the Pacific Coast Oto-Ophthalmological Society and 240 members of the American Academy of Ophthalmology in the eastern United States. See appendix c. 94

Supplementary Studies T h e optometrists returned 279, or 44.3 per cent, and the ophthalmologists 261, or 52.2 per cent, of the questionnaires. T h e r e were 29 unusuable replies, 15 from optometrists and 14 from ophthalmologists, most of them without appropriate criteria indicated. Some suggested scholastic achievement or retarded reading should be the criteria, and several stated that any child referred by a screening program for any reason would be considered a correct-referral regardless of the presence or absence of anomalies of vision. TABLE

28

QUESTIONNAIRE: VISUAL ACUITY

Best visual acuity that constitutes a correct referral (N = 511) Numerical measure

Optometrists

Ophthalmologists

Together

Vision Poorer E y e (without glasses or with present glasses)

Mode

20/30

20/30

20/30

20/30

20/20 to 20/60

20/20 to

20/70

20/30 20/30 20/20 to

20/70

Q,

20/30

20/30

20/30

Q3

20/30

20/40

20/40

Vision Difference Between Eyes (lines on Snellen acuity chart) Median Mode Range

Q. Q.
=>

Si 5 co > oo U J oce o L.

Supplementary Studies ing. For example, if 2 0 / 4 0 is chosen as the "failure" line, myopia of up to - 0 . 5 0 D.S., hyperopia of up to +4.75 D.S., and astigmatism in certain combinations up to - 1 . 5 0 D.C., would be expected to pass. T h u s the child who "fails" visual acuity probably will have a significant refractive error, but many of those who "pass" may also have significant refractive errors that go undetected.

101

IX Recommended Design For a Vision Program For Elementar/ Schools

T h e staff of the Orinda Vision Study was dedicated to the idea of making the study findings of immediate and practical use to those concerned with the vision problems of elementary-school children. T h e following recommendations are based on the data in this report and on our experiences in the practical application of vision-screening programs. These recommendations are unanimous.

STEERING COMMITTEE Certain groups must share the responsibility for the visual health and welfare of children in the elementary schools. By law, in California, the school administrator is charged with providing "adequate" vision tests for school children. T h e public-health and school-health authorities of a community have a broad responsibility that certainly includes the visual health of elementary-school children. T h e two professions concerned with vision care, ophthalmology and optometry, have a direct responsibility in providing guidance for a vision program and in supplying professional services. Parents must assume the final responsibility for their children's visual welfare and can participate in the school-health program through parent organizations. Representatives of these groups (school administration, public or school health, optometry, ophthalmology, parents) should be organized into a steering committee in each school district or organizational unit. All groups should be represented in order to obtain the necessary community support for the program. It should be the responsibility of the superintendent of schools to call this committee into being and he, or his representative, should serve as chairman. This committee should perform the following services. Review available information on vision screening and decide on the most efficient vision-screening method. Determine the criteria and cut-off points for the vision-screening method to be used. Determine the qualifications of the personnel to be employed to do the vision screening.

102

P r o g r a m for Elementary Schools Obtain the acceptance of the groups the committee members represent for the program decided upon. Participate in the formation and operation of the visual-health education program. Review the vision-screening program at intervals to make sure that it is accomplishing its objectives.

VISION SCREENING T h e most efficient method of screening elementary-school children for vision problems, as shown by this study, is the Modified Clinical Technique. It has been shown that, if this method is used once, it will identify almost all those children with vision problems at that time and make few unnecessary-referrals. In succeeding years the few new failures may be found by Snellen visual acuity testing and Teacher Observation. Those with previously identified vision problems should be re-referred without tests. Those failed by the visual acuity tests or picked u p by Teacher Observation should be retested by M C T before being referred for professional attention. This will minimize needless referrals. It is recommended that the M C T be used at the first-grade level in order to place those children with vision problems under professional care as soon as possible. This method was equally efficient at all grade levels although the optometrists who used this method stated that it was easier to test the older children. T h e recommended program consists of using the M C T for all first graders and all new entrants to the school system above this grade. Visual acuity testing should be given annually to all children except those scheduled for the M C T and those previously identified as having vision problems. All children failing the visual acuity test or suspected of having vision problems by Teacher Observation should be sent to the professional screener for retesting by the M C T before referral for eye care. Parents of all children with known visual problems should be reminded annually of the need for regular vision attention for their children. In the conversations with parents whose children were referred by this screening program, it was frequently noted that some parents delayed professional attention, awaiting confirmation of the need by the next annual screening. Parents seemingly doubt the validity of a single screening referral, and postpone care for their children. An important part of a vision program should be the promotion of visual-health education that reaches teachers, children, and parents and that stimulates the use of regular professional attention for those children with vision problems.

Modified Clinical Technique T h e following tests are used in screening with the M C T . 1. Visual acuity. This is measured with a table-model projector-type instrument (e.g., American Optical Company Projectochart Model 1217) and appropriate slides for both letters and illiterate E charts projected on a screen at twenty feet. 2. Cover test. With the above projector, showing a single threshold letter on the screen, and an occluder, both the cover-uncover and alternate-cover tests at a distance of twenty feet are performed. A loose prism of 5 prism diopters may 103

Program for Elementary Schools be used for accurate determination of coordination at the cut-off point. With a single threshold letter held at 16 inches and with 6 prism diopter and 10 prism diopter loose prisms, the coordination at the near point is determined by the cover test. 3. Skiametry. T h e equipment required includes a small movie projector and screen, a retinoscope, 2 pairs of +1.50 D.S. lenses in trial frames, and a test lens bar. The child being tested observes a cartoon film projected on a screen at a distance of twenty feet through a pair of +1.50 D.S. lenses. Since it is desirable to have the child look through the lenses for at least one minute before the test is made, the lenses can be placed before the child's eyes and he can observe the film while the examiner performs test 1 and test 2 on the next child. When the retinoscopy test is being performed, the lens bar containing lenses of -0.75, +0.75, +1.50, +2.25 D.S. is held in front of the lenses in the trial frame. T h e best estimates of the total refractive error for the vertical and horizontal meridians are recorded separately. Only if there is a marked oblique astigmatism are other meridians reported. T o reduce recording errors, the vertical meridian should always be reported first. 4. Organic problems. With a hand magnifier and ophthalmoscope, external and internal organic problems are checked for. Because the M C T is flexible, other tests can be included. For example, color tests can be added if desired. T h e above tests are considered to be the minimum necessary to find essentially all those with vision problems needing professional attention. It provides for an objective test of refractive error to be compared with the subjective visual acuity, and objective tests of coordination and organic problems. Snellen Test The Snellen test for visual acuity should be given annually to all children except those scheduled for the M C T and those with known vision problems. 1. A visual acuity chart of black characters on a white background with selfcontained illumination (e.g., Good-lite Eye Chart Model A); with both letter characters and illiterate E charts, at 20 feet. 2. The visual acuity of each eye should be tested separately and recorded as the Snellen notations for the line of the smallest figures identified correctly with no more than 2 figures missed per line. A hand-held ocluder of white, opaque, washable plastic should be placed before the eye that is not being tested, and both eyes should be open at all times. T h e child should not be allowed to "squint" or "narrow eye lids" to see the chart. 3. Those failing the visual acuity test should be sent for retest by the M C T . Teacher Observation Teacher Observation for visual problems, should be done continuously. Those suspected of having problems associated with vision should be sent for vision screening by the M C T or, if the M C T is not available, to the nurse for consideration of referral for professional attention. There are four general types of symptoms that deserve particular attention. 104

Program for Elementary Schools 1. Evidence of ocular abnormalities—crusted, red-rimmed, swollen lids, frequent sties, watering or bloodshot eyes, crossing of the eyes. 2. Complaints of visual distress—sensitivity to light, b u r n i n g or itching of eyes or lids, blurring or seeing double, words and lines r u n n i n g together, words jumping, headache. 3. Performance which suggests eye difficulties—rubbing eyes frequently, blinking frequently when reading, "screwing u p " face when reading, closing or covering one eye or tilting head to one side when reading or watching classroom movies, abnormal posture when doing close work, holding work too close or too far, irritableness, short attention span, tenseness in reading. 4. Evidence of difficulty or dislike or inattention for reading, reading subjects, fine work.

CRITERIA FOR VISION SCREENING T h e criteria and cut-off points derived by the special techniques discussed in chapter HI and in chapters vi and v m are as follows. 1. Modified Clinical Technique. These criteria for referral are used: Modified Clinical Technique

Visual acuity Refractive error Hyperopia Myopia Astigmatism Anisometropia Coordination Tropia Esophoria Exophoria Hyperphoria Organic

Criteria of referral

20/40 or poorer either eye +1.50 -0.50 1.00 1.00

D.S. or more D.S. or more D.C. or more D. or more

Distance

Near

Any 5 4 or more 5 4 or more or more

Any or more 10A or more 2A or more

Any pathology or medical anomaly of the eye and/ or adnexa

2. Visual acuity (Snellen). Refer for M C T all those with 20/40 or poorer visual acuity in either eye. 3. Teacher Observation. Refer for M C T (if readily available) or to school nurse all those with evidence of visual problems or performance which suggests eye difficulties. These methods and criteria will not identify every child with a vision problem, b u t will identify almost all of them. Some more obscure problems, such as aniseikonia and the more rare forms of accommodative-convergence problems, may be overlooked, b u t their rate of occurrence in the population is so small as to make it impractical to test for them. 105

P r o g r a m for Elementary Schools

QUALIFICATIONS FOR PERSONNEL T h e efficient operation of the vision program as outlined requires specialized personnel with specific qualifications. T h e necessary skills are taught as part of the curriculum of optometry schools and departments of ophthalmology. 1. For the Modified Clinical Technique. T h e following minimum requirements are recommended for the examiner: (i) certificate in optometry from an accredited school of optometry; or (ii) completion of at least four years of college courses leading toward a degree in optometry in an accredited school of optometry; or (iii) an M.D. degree with one year of specialized training in ophthalmology in an accredited medical school or hospital; or (iv) an M.D. degree and, if lacking formal training, two years of practical work in ophthalmology. T h e professional examiner should be an employee of the agency responsible for the school health program on either a part-time or full-time basis. It is considered of importance to insist that the professional examiner not be in private practice anywhere in the area so that the economic interest of the examiner cannot become an issue. 2. For Snellen Visual Acuity Screening. T h e person giving the visual acuity tests may be the regular school nurse or a person specially employed for the short periods of time necessary to perform this test. This latter person, available for part-time work, may be a former school or public-health nurse who has had experience in vision testing. This person could receive additional training or assistance, if needed, from the professional examiner. It may be advisable to employ a specially trained person to cover all the schools in the district and thus provide uniform testing. T h e employment of a nurse tester would avoid the significant cost of teacher training as well as teacher screening. 3. For Volunteer Assistants. T h e parents organization should be invited to assist in the screening program by supplying two volunteers for each session of testing. One volunteer would serve as recorder and the other would serve to maintain order and organization at the testing site. This procedure has proven to be very effective, and most of the mothers who have served in this way feel that it was a worthwhile experience. This parent experience helps to further the visualhealth education program. As many parents as possible should be given the opportunity to participate in this program.

COSTS OF SCREENING T h e M C T will require, on an average, 4.5 to 5 minutes per child. At the rate of $6.00 per hour (which was the rate paid part-time professional personnel by the Contra Costa County Health Department), the average cost is between 45 and 50 cents per child. T h e M C T would be given only to first graders, new entrants, and to those failing the visual acuity test or those referred by Teacher Observation. T h e total cost would be quite low, and the efficiency would be high. T h e time for visual acuity testing is 2.5 to 3 minutes per child, on an average. Since no plus sphere test is included and no retesting is required, this is considerably less than the time required to perform the California State Recom106

Program for Elementary Schools mended Procedure. At a salary rate of $3.50 per hour, the cost of visual acuity testing would average between 1 4 ^ and 171/i, cents per child. All children would be tested for visual acuity annually who had previously received the M C T and passed it as non-referrals. (All those with identified vision problems to be rereferred annually without vision screening.) For purposes of illustration, let us assume an elementary school of six grades with 1,000 students. T h e breakdown, showing costs, is as follows: Modified Clinical Technique: 200 grade 1 50 new to school, in grades 2 to 6 30 referred by visual acuity test, grades 2 to 6 90 referred by Teacher Observation, grades 2 to 6 370 children at $0.50 = $158.00 Visual acuity testing: 800 grades 2 to 6 -200 children (25 per cent) with previously identified problems 600 children at $0.16 = $96.00 Thus for an annual cost of approximately $281.00 per thousand children the recommended vision-screening program will identify 98 per cent of those children with vision problems. There will be a minimum of over-referrals. T h e cost of carrying out an annual screening for one thousand children with the CSRP would be approximately $530.00, not counting any teacher or nurse training time, and it would miss 75 per cent of those needing professional attention.

REFERRAL RECOMMENDATIONS Only those children who do not meet the criteria of the M C T should be referred for professional vision attention. Children failing the Snellen visual acuity test or suspected of having a vision problem by Teacher Observation should be referred to the professional examiner for further screening on the MCT. If Teacher Observation suggests visual difficulty after the M C T has been completed, those children should be sent to the nurse for consideration of referral for professional attention. T h e suggested form on which the referral is made is shown in figure 19. The key words are italicized. Attention does not imply glasses or treatment, which is left to the doctor's decision. Non-diagnostic reminds all concerned of the nature of screening tests. Evaluate means just that, and removes the problem of the irate parent whose child was "referred for care" only to find that the child needed none. It places the responsibility for diagnosis with the doctor, where it belongs. T h e parent's signature on the form to provide a release for the professional information is considered essential. It will remove one serious problem of legal responsibility from the minds of the optometrists and ophthalmologists of the community and facilitate the return of information to the school. For those children previously identified as having a vision problem, a reminder notice is suggested (see fig. 20). 107

FIGURE

19

VISION REFERRAL AND REPORT FORM School Address Nurse D E A R PARENT:

is being referred for professional vision attention because he/she did not perform satisfactorily on our school screening test at this time. Since these tests are non-diagnostic and only rough measures of visual performance, we believe that it is in the best interest of each such child to have his vision evaluated by a professional person specially qualified in vision care to see if treatment is necessary. We believe that your child will be helped if this matter is given your attention as soon as possible. Your signature below will authorize your child's eye examiner to return the important information to the school nurse. We thank you for your coopération.

Parent's Signature

Date

Principal

D E A R DOCTOR:

T h e above named child has not performed satisfactorily on our vision screening tests in the school. Our observations indicate the possibility of visual difficulty in the areas checked: Visual acuity , Refractive error , Coordination , Organic Please return the information requested together with your recommendations as soon as possible. This will be helpful to the teacher and to me in arranging this pupil's program. E Y E EXAMINER'S REPORT TO THE SCHOOL Visual Acuity:

Without lenses With lenses Refractive Error: R . E (general statement) L.E Coordination: (general statement) Organic (general statement) Prognosis

R.E R.E

L.E L.E

Were glasses prescribed: Yes , No ; Unbreakable: Yes, Glasses should be worn: constantly , for class only , reading Preferential seating recommended Child should return for further care Other recommendations or suggestions

Date

Both Both

No ... , other

Signed Address

Phone

FIGURE

20

VISION REFERRAL AND REPORT FORM School Address Nurse D E A R PARENT:

According to our records your child has had a vision problem and is not being given vision screening tests at the school. You have probably provided professional vision attention for him, but we would like to take this opportunity to remind you that children with vision problems require regular care. T h e i r eyes do change as they grow and develop. Professional persons specially qualified in vision care generally recommend, as a minimum, an annual examination for children with vision problems to maintain their vision ability. Please check with your eye examiner. Your signature below will authorize your child's eye examiner to return the important information to the school nurse. We thank you for your cooperation.

Parent's Signature

Date

Principal

D E A R DOCTOR:

T h e above named child has not been given a school vision screening because of a past history of vision difficulties. Please return this information and your recommendations to the school nurse. This will be helpful to the teacher and nurse in arranging this pupil's program.

E Y E EXAMINER'S REPORT TO THE SCHOOL Visual Acuity:

Without lenses With lenses Refractive Error: R . E (general statement) L.E Coordination: (general statement) Organic (general statement) Prognosis

R.E R.E

L.E L.E

Were glasses prescribed: Yes , No ; Unbreakable: Yes Glasses should be worn: constantly , for class only , reading Preferential seating recommended Child should return for further care Other recommendations or suggestions

Date

Both Both

, No .... , other

Signed Address

Phone

P r o g r a m for Elementary Schools

ESTIMATED RESULTS OF S C R E E N I N G T h e results obtained in this study are subject to sampling errors and the influence of the amount and kind of previous professional care, and they may vary with communities of different socioeconomic status. From the results of this study the following estimates are given. These should serve as rough guides only, for other results will be modified by local circumstances. These figures are based on the testing of 454 first graders in the Orinda Vision Study in 1954 and 1955. Modified Clinical Technique If a large number of first-grade children are given the M C T , approximately 18 per cent will fail the screening, as many as 30 per cent of whom may have had previous professional attention. Approximately 2 per cent of those referred will be unnecessary-referrals. Most of the children who are referred by the M C T will fail more than one of the criteria. If 18 per 100 fail the screening, the approximate number failing each criterion will be: 8 will probably fail visual acuity, 11 will probably fail refractive error, 9 will probably fail coordination, 2 will probably fail organic, and 2 will probably be unnecessary-referrals. T h e amount of previous professional care will influence the number failed. In communities where professional attention is much less "available" than it is in Orinda, the referrals may run as high as 20 per cent. This study was conducted in a community at the upper end of the socioeconomic scale, and variations both in the incidence of vision problems and in previous professional attention may occur in dissimilar communities. If the M C T is used for children in grades higher than the first grade, the number failing will be increased by about 1 per cent per grade, again influenced by previous professional attention. This will be due largely to increased failures in visual acuity and refractive errors. Visual Acuity and Teacher Observation Snellen visual acuity testing in successive years of those children without previously identified vision problems should result in the failure of about 4 to 5 per 100, 2 or 3 of whom may be unnecessary-referrals when rescreened by the M C T . Teacher Observation in successive years may identify as many as 15 per 100, most of whom will be unnecessary-referrals when rescreened by the M C T . This, however, will help to detect the borderline new-referrals. Inflammatory or traumatic conditions or sudden changes in visual behavior deserve prompt referral to the nurse. VISUAL-HEALTH E D U C A T I O N This study has indicated a definite need for visual education. Instruction on care of the eye, eye health, eye safety, how we see, and so forth, should be part of the educational program of the school. Visual-health education should also reach the parents, especially with information on eye health, eye safety, and 110

Program for Elementary Schools eye problems common among children. It should also create family interest in obtaining regular professional attention for children with vision problems. It is not within the province of this study to detail a visual-health education program as this was not the subject of our study. However, our experience indicates the following points deserve emphasis. 1. Children do not outgrow vision problems. It is those children with vision problems who change the most and require the most f r e q u e n t professional attention. T h e changes will be most rapid among the myopes. 2. Coordination problems, usually present by age 6, generally require longterm therapy and require frequent professional attention. Parents should be alerted to the need for early diagnosis, early attention, and long-term therapy. 3. Organic problems are of two types. T h e inflammatory and traumatic conditions require prompt professional care and treatment. T h e congenital problems should receive professional attention. 4. Not all vision problems may be discovered by a vision-screening program. Parents and teachers should be alert to the possibilities of such problems, and should not ignore performance suggestive of visual problems.

EDUCATIONAL POLICY T h e study staff recognizes that the school is an educational institution and that all programs, including school health, should be basically educational in nature or contribute to the educability of the children. It has been stated that one of the reasons for the recommendation that teachers screen, especially in the elementary school, was that screening could be carried on as part of the regular classroom program and that instructional units on the eye, eye safety, and so on, could be "tied in" with the screening. T h i s would be satisfactory if the teachers were trained and equipped to do an efficient job of screening. As shown in this study, however, observation and screening done by teachers with the California State Recommended Procedure are not satisfactory. Both in terms of cost and efficiency the program recommended in this study is far superior. It is not necessary to sacrifice the educational opportunities involved in a teacher-operated screening program simply because a professional examiner is employed to do the screening. T h e screening program does not need to become isolated and significant only for case finding. As recommended in this report, increasing emphasis should be placed on visual-health education. Instructional units could be constructed around the Modified Clinical T e c h n i q u e just as easily as around the California State Recommended Procedure. In fact, both the professional examiner and members of the steering committee should contribute to this development and should be available to answer questions, consult on special problems, and assist in the integration of the vision screening with the general educational program.

Ill

X Summary and Conclusions

A review of previous vision-screening studies of elementary-school children reveals that most, if not all, of the studies were deficient in certain respects. For example, these deficiencies include: Lack of definition of what constituted a vision problem or need for professional vision attention. Absence of evaluation of both under-referrals and over-referrals in estimating screening efficiency. No study of the effect of previous professional care. Failure to include all interested groups in the study in order to consider all the problems involved and failure to use the help of people in education, public health, optometry, and ophthalmology. Failure to use longitudinal follow-up of individual children in successive years, to check on adequacy of screening, and to determine optimum screening intervals. Lack of a specific plan for a school vision program. A more comprehensive study was further prompted by the State of California requirement for adequate vision tests for all elementary school children. Neither the adequacy nor the interval of screening is clearly defined. T h e Orinda Union School District was chosen as a test situation, and 1,163 children, approximately 95 per cent of the enrollment, were examined in 1954 (first through the sixth grades). Of these, 1,032 were tested again in 1955 and 941 again in 1956, so that 941 were tested all three years. Some 221 children were arbitrarily chosen for clinical study as a control group in 1954 to study the problem of under-detection by the screening methods; of these, 190 were still available and clinically retested in 1956. Other supplementary groups were included for a study of different phases of the project. No attempt was made to correlate vision problems with scholastic or social achievement. No attempt was made to study the results of correction of present ocular difficulties and the prevention of future vision problems (prevention of myopia, etc.).

112

S u m m a r y a n d Conclusions Seven different screening methods were used. T h e screening results were compared with clinical evaluations of all referrals at the University of California School of Optometry and the Stanford University School of Medicine Department of Ophthalmology. Of the screening methods studied, the most efficient was the Modified Clinical Technique. T h e clinical criteria of need for professional attention (correct-referral) adopted for this study were derived from an analysis of the clinical information and the joint decisions of the study staff. These compared favorably with the criteria cited in a questionnaire on vision screening received from ophthalmologists and optometrists throughout the United States. T h e need for professional attention, not necessarily treatment, was the basis for the evaluation of the screening referrals by the study staff. T h e professional decisions were described in terms of four criteria: visual acuity, refractive error, coordination, and organic problems. A child was considered to be a correct-referral if he failed to meet the study criteria. For a listing of the criteria, see p. 32. No need for variations because of age or sex was found in the clinical criteria. T h e incidence of vision problems increased with age at a rate of approximately 1.6 per cent per year. Of the age group 5-6-7, 18 per cent had vision problems, which increased to 31 per cent in the age group 13-14—15. T h e proportion of children who have had some professional attention increased with age. In 1954 more than half of those who had previously received professional attention were still correct-referrals, but almost all of them could be equipped to pass the vision criteria of this study with further care. T h e vision measurements of children with vision problems changed more than they did for other children. Those children with vision problems need the most frequent professional vision attention. Nurses and teachers should re-refer, at least annually, all children known to have vision problems. No significant differences were found in these results due to sex. T h e first testing program in 1954 detected most of the refractive errors, essentially all the amblyopias, tropias, phorias, and most of the significant organic problems, particularly those of congenital origin. T h e new-referrals found in successive years were primarily children with refractive errors, and mainly those developing myopia. Inflammatory or traumatic organic problems, such as blepharitis, styes, or injury, accounted for some of the new, but usually transient, problems. T h e newly developing organic problems usually declare themselves and do not require special screening tests. After the initial testing program using the M C T in 1954, the new referrals found as a result of retesting in 1955 and 1956 could have been found by simple visual acuity (Snellen) screening combined with Teacher Observation. T h e Modified Clinical Technique (MCT), shown to be far superior to the other vision-screening methods tested, was very satisfactory in minimizing both under-referrals and over-referrals. It costs approximately 45 cents per child to carry out. T h e costs of the other screening methods studied were 37 cents for the Massachusetts Vision Kit (MVK), 43 cents for the Telebinocular, and 53 cents for the California State Recommended Procedure (CSRP). 113

Summary and Conclusions T h e most significant over-all cost in a vision-screening program will be the expense to the individual families, or to the community resources, for clinical examinations of the children screened out as needing professional attention. If there is significant over-referral, the cost will be increased needlessly. In addition to wasting community resources, over-referrals may well destroy confidence in the program. If there is significant under-referral, many children needing professional attention will not be detected, although screening costs will be minimized. In terms of visual health and welfare, the hidden costs of under-referrals are inestimable. Only the M C T avoided significant over-referral as well as underreferral. A steering committee should decide whether one of the color-discrimination tests should be used, and its results made a part of the record for counseling purposes. T h e investigators unanimously agreed that a successful vision-screening program could be set u p in the following manner. 1.A steering committee, with representatives from education, ophthalmology, optometry, public health, and parent groups, should develop the program. Through its professional members, the committee should obtain acceptance of the program and screening criteria by the professional people in the community who are concerned. 2. A qualified professional examiner should be employed to screen, with the M C T , all children in the first grade and all new entrants to the elementary school at that grade or above (see chap. ix). Children who have had the M C T once and were found to be non-referrals should be tested annually thereafter with the Snellen test. Teacher Observation should be done continuously. If feasible, the Snellen testing and the reports of Teacher Observation should be completed before the annual visit of the professional examiner. In this way children failing the Snellen or referred by Teacher Observation could be screened by the M C T at the same time as the first graders, and before being referred for private professional attention. 3. T h e Snellen test (described in chap, ix) could be given by a qualified tester hired by the school to do the work once each year. This would avoid the significant cost of teacher training as well as teacher screening. 4. Those children failing the M C T should be referred for professional vision attention. 5. T h e parents of those children with known visual problems should receive a reminder that their children need regular professional attention at least once each year without screening. 6. T h e professional examiner should act as an employee of the agency responsible for the school health program and, even if he is a part-time employee, should not be in private practice in the area so that the economic interest of the examiner cannot become an issue. 7. T h e school health-education program should include material on visual health that influences parents to get regular professional attention for those children with vision problems. 8. T h e administrator responsible for the vision-screening program in the schools 114

Summary and Conclusions should receive from the professional examiner an analysis of the cases referred. These results should be compared with the estimates cited in this study (see p. 110), for a check on the effectiveness of the program. Significant departures should be studied carefully. Modified Clinical Technique. If a large n u m b e r of first-grade children are given the M C T , approximately 18 per cent will fail the screening, u p to 30 per cent of whom may have had previous professional attention, and approximately 2 per cent will be unnecessary-referrals. Most of the children who are referred by the M C T will fail more than one of the criteria. T h e amount of previous professional attention will influence the n u m b e r failed. T h e referrals may be as high as 20 per cent. If the M C T is used for children in grades above the first grade, the n u m b e r failing will be increased by approximately 1 per cent per grade, owing largely to increased failures in visual acuity and refractive errors. Visual Acuity. In successive years the visual acuity (Snellen) testing of those children previously screened by M C T and without identified vision problems, should result in the failure of u p to 4 or 5 per 100, 2 or 3 of whom may be unnecessary-referrals when rescreened by the M C T . Teacher Observation. In successive years Teacher Observation of those children previously screened by M C T and without identified visual problems, may fail as many as 15 per 100, most of whom will be unnecessary-referrals when rescreened by the M C T . This, however, will help to detect the borderline newreferrals. T h e steering committee should have the obligation of verifying the adequacy of the screening program, the absence of excessive under-referrals and over-referrals, and the modification of the referral criteria to meet local requirements, and should also assist in the development of the school visual-health education program. Vision is the primary avenue to education and the identification and removal of visual handicaps most certainly will increase the educability of children with vision problems, improve their visual health, and be of ultimate benefit to the community. T h e study staff believes that the vision program recommended here will contribute significantly to the general educational program.

115

APPENDIX A

Test-Retest, Part Tests, and Vision Changes with A g e

The screening methods can be analyzed in two ways that are of interest, though not essential, to the main themes of this study. For three of the visionscreening methods used in this study—California State Recommended Procedure, Massachusetts Vision Kit, and Telebinocular—the recommended procedure is to retest all those children who fail the first test before referring them for professional vision attention in the community. Referrals are only those children who fail the method twice. In 1956 this test-retest procedure was followed exactly and the results are shown in chapter iv. However, for two of the methods—MVK and Telebinocular—all children, not just those who failed the first test, were given two screening tests. For the CSRP, MVK, and Telebinocular we can analyze the effect of the retest on the effectiveness of the method, and on the MVK and Telebinocular we can compare the results of the first test with the second test on all the children. These comparisons constitute the test-retest analysis. A second analysis of interest is the relation of the results of the part tests of each screening method to the clinical criteria. From this analysis it is possible to see which part tests were more successful in finding children with vision problems and which particular clinical criteria, or combinations of criteria, were failed or passed by each child on each part test. TEST-RETEST The first six tables in this section are based on the tabular system discussed earlier (p. 18) and show the relation between the clinical evaluation (correct-referral, unnecessary-referral) and the screening-test results (passed, failed). The phi () coefficient is calculated for each of these distributions and can be interpreted to indicate the relative efficiency of each screening method. California State Recommended Procedure In 1956 this method was done by specially qualified school nurses. All children who failed the first test were retested on the same equipment by the same nurses within three weeks of the original test. The results of 1956 test-retest for the 1,269 children on which this information was available are as follows: 117

Appendices Results of test 1 alone (compared to clinical criteria): Clinical Criteria 0 = +0.37

CSRP Test 1

Correctreferral

Unnecessaryreferral

Total

Failed

62

29

91

Passed

158

1,020

1,178

Total

220

1,049

1,269

Results of test I plus retest of those failing test I (compared to clinical criteria): Clinical Criteria 0 = +0.41

Failed test and retest CSRP Test and retest

Correctreferral

Unnecessaryreferral

Total

54

10

64

Passed

166

1,039

1,205

Total

220

1,049

1,269

So the addition of the retest for those failing the first test improved the phi coefficient slightly. T h e retest: 1. Reduced the total referrals (91) by 27, a 30 per cent decrease (27/91). 2. Reduced the correct-referrals by 8, a 13 per cent reduction (8/62), and therefore the under-referrals increased by the same amount. 3. Reduced the over-referrals by 19, a 66 per cent reduction (19/29). Massachusetts Vision Kit I n 1956 all children were given the MVK twice within a three-week period. T h e same equipment and personnel were used. T o be classified as a referral for the analysis described in chapter iv, the child must fail both test and retest, as specified by the manufacturer's recommendations. T h e following two tables show the effect of the retesting on only those who failed the first test. Results of test 1 alone (compared to clinical criteria): Clinical Criteria 0 = +0.53

MVK Test 1

Unnecessaryreferral

Total

Failed

125

84

209

Passed

77

892

969

202

976

1,178

Total

118

Correctreferral

Appendices Results of test 1 plus retest of those failing test I (compared to clinical criteria): Clinical Criteria 4> = + 0 . 5 9

MVK Test and retest

Failed test and retest Passed Total

Correctreferral

Unnecessaryreferral

Total

in

33

144

91

943

1,034

202

976

1,178

So the addition of the retest for those failing the first test improved the phi coefficient slightly. T h e retest: 1. Reduced the total referrals (209) by 65, a 31 per cent reduction (65/209). 2. Reduced the correct-referrals by 14, an 11 per cent reduction (14/125), and therefore the under-referrals increased by the same amount. 3. Reduced the over-referrals by 51, a 61 per cent reduction (51/84). Telebinocular In 1956 all children were given the Telebinocular test twice within a three-week period. T h e same equipment and specially trained personnel were used. T o be classified as a referral, the child had to score either fail or questionable on the first test and fail on the retest, as specified by the manufacturer's recommendations. T h i s procedure was followed in the analysis in chapter iv. T h e following two tables show the effect of this retesting. Results of test 1 alone (compared to clinical criteria): Clinical Criteria = + 0 . 5 2

Telebinocular Test 1

Correctreferral

Unnecessaryreferral

Total

Failed

145

131

276

Passed

57

846

903

202

977

1,179

Total

Results of test 1 plus retest of those who were failed or were questionable on test 1 (compared to clinical criteria): Clinical Criteria * = +0.51

Telebinocular Test and retest

Failed or quest, test 1 and failed retest Passed Total

Correctreferral

Unnecessaryreferral

Total

113

67

180

89

910

999

202

977

1,179 119

Appendices So the addition of the retest of those who failed or were questionable on test 1 reduced the phi coefficient insignificantly. The retest: 1. Reduced the total referrals (276) by 96, a 35 per cent reduction (96/276). 2. Reduced the correct-referrals by 32, a 22 per cent reduction (32/145), and therefore the under-referrals increased by the same amount. 3. Reduced the over-referrals by 64, a 49 per cent reduction (64/131). Reliability Estimate

All the children were given both the Massachusetts Vision Kit and the Telebinocular twice in 1956. An estimate of the reliability of these two tests can be made from the following two tables. In the upper part of each box is the number of correct-referrals (c) and in the lower part is the number of non-referrals (n), as determined by the clinical criteria. For example, 111 c/33 n shows that these 144 children failed both test and retest. Thus, of those who failed twice, there were 111 correct-referrals and 33 non-referrals, who because they failed the screening are 33 over-referrals. Massachusetts Vision Kit, 1956 Test 2 Total

Passed

Failed

14 c

111 C

125 c

51 n

33 n

84 n

55 c

22 c

77 c

813 n

79 n

892 n

69 c

133 c

202 c

864 n

112 n

976 n

Failed

Test 1

Passed

Total

Telebinocular, 1956 Test 2 Passed

Questionable

Failed

Total

19 c

18 c

108 c

145 c

51 n

36 n

44 n

131 n

4c

7c

5c

16 c

53 n

35 n

23 n

111 n

29 c

8 c

4 c

41 c

683 n

27 n

25 n

735 n

52 c

33 c

117 c

202 c

787 n

98 n

92 n

977 n

Failed

Questionable

Passed

Total

120

Appendices T h e Telebinocular gives results in three categories: pass, questionable, and fail. These are compared to the clinical determinations of correct-referral (c) and nonreferral (n).

PART TESTS For those interested in the performance of the various part tests in each screening method, the results are shown in figures 21-23. T h e combinations of the four clinical criteria form the columns. T h e number failing each combination, according to the clinical examinations, is presented for each year. T h e rows represent failures on the various screening methods and their part tests as related to these clinical criteria. By inspection it is possible to determine if a given test was successful in identifying certain types of vision problems or if a particular test had a substantial over-referral rate.

ADDITIONAL CONSIDERATION OF VISION CHANGES WITH AGE Figures 24, 25, 26 were prepared from the study data to demonstrate the underlying changes that take place in the visual characteristics of children from age 5 to age 15. An understanding of these underlying changes is necessary for any one designing or administering a vision-screening program. T h e basic changes in the rate of failure with age for each of the criteria are shown in figure 24. This shows the increase in the percentage of children who fail myopia (-0.50 D.S. or more) though it does not show the change of the amount of myopia for those already classified as myopic. It shows the rate of change in failure of visual acuity (20/40 or less), and the fact that visual acuity is directly related to the increase in myopia. T h e other criteria—-hyperopia, astigmatism, anisometropia, coordination, and organic problems—all show a rather constant failure rate with age. Thus it may be concluded that all the criteria, except myopia, are relatively independent of age. This conclusion agrees with the visionscreening program proposed in chapter ix in which the M C T is used for the firstgrade level followed by regular screening with a visual acuity test to pick up those children becoming myopic. The changes in visual acuity with age are shown in figure 25. Two aspects of visual acuity are considered. One is the visual acuity with the best refractive correction and represents the best visual acuity attainable on the basis of retinal sensitivity. This is shown to improve with age (the mean and the standard deviation decrease). T h e other aspect is the change in unaided visual acuity, which shows the changes that would occur if glasses and other therapy were not available. Here the mean acuity improves from age 5 to age 8, and then rapidly gets poorer. T h e standard deviation increases over the age range, indicating that those with poor acuity tend to get poorer without some help from glasses. This indicates, in terms of visual acuity, the value of a vision-screening and visual-correction program for children in this age range. Figure 26 shows the changes in the spherical refractive error (myopia-hyperopia) from age 5 to age 15. It demonstrates that the mean refractive error decreases

121

Appendices with age faster than the median and that the standard deviation increases at the same rate that the mean decreases. This is one more proof that the decrease in the average refractive error is due to rather large increases in myopia in those children already myopic and not due-'to a general trend toward myopia of all the children. Those who were significantly hyperopic (+1.50 or more) did not become less hyperopic. It would seem that the common conception of "growing out of hyperopia" is erroneous. This data on refractive changes supports the criterion regarding hyperopia used in this study, and contributes to our understanding of the nature of the changes that may be expected in this age range. Children obviously do not "outgrow" vision problems as they get older. Early detection and regular attention are necessary if children with visual problems are to have adequate vision. Most of those first-grade children with hyperopia, astigmatism, anisometropia, coordination problems, and the more serious organic problems can be discovered by screening with the MCT. Those children developing myopia can be discovered as the changes occur by regular visual acuity testing.

122

FIGURE

PART-TESTS

21

FAILED

o M

1954

u

Im

g

1 . CLINICAL CRITBtIA

2. TKACHHt OBSERVATION DNDIR-RKFERRALS REFBtRAIS part tests f a i l e d

a. b. c. d. a. f. g. h. 1. J.

Without pertinent comment 3treine to see, squints Tilts head Eyes turn In or out Blepharitis, styes Eyes water, blinking Poor visual acuity Holds book close Nervous twitching of eyas One aye larger, protrude«

3. NURSE OBSERVATION UNDER-REFERRALS REFERRAI3 PART TESTS FAILED a« Without pertinent coment b. Strains to sea, squints c. Tilts head d. Eyes In or out a. Blepharitis, atyes f . One eye larger, protrudes 4. STATE RECOMMENDED PROCEDURE UND Et-REFERRALS REFERRALS PART TESTS FAILS)

a. Teaoher Test 1) Visual acuity 2) +1.50 D. Sphere 3) +2.00 D. Sphere 1 ) Cover t e s t b. Nurse Re-Test Ì) Visual aoulty 2) +1.50 D. Sphere 3) +2.00 D. Sphere 4) Cover test

5. utflfry-iniBITS VISION KIT UNDHt-REJERRALS REFERRAIS FART TESTS FAILED a. Visual Acuity 1) 20/50 or less (Or. 1-3) 2) 20/40 or less (Gr.4-6) b. Plus Sphere Test 1) +2.25 D.S. (Or.1-3) 2) +1.75 D.S. (Or.¿-6) c. Coordination 1) U t e r a l phorla 2) Vertical phorla 6. MODIFIED CLINICAL TECHNIQUE UNDER-REFERRALS REFERRAI3 PART TESTS FAILED a. Visual Acuity b. Skiametry c. Cover Test d. Inspection for Organic Prob.

219

9

43

44

18

46

11

12

6

2

1

18

6

5 4

33 10

31 13

12 6

27 19

7 4

7 5

2 4

1 1

1

12 6

5 1

1 2

6 5 3

3

1 1

1

1

1

278

203

144 75

33 88 51 33 31 14 9 7 6 6

22 62 42 20 23 12 4 6 6 6

11 26 9 13 8 2 5 1 0 0

59

35

195 24

U 10 4 17 8 6

6 6 2 11 6 4

8 4 2 6 2 2

174

79

124 95

(333) 104 99 28 195

(202) 33 77 13 159

(131) 71 22 15 36

72 35 16 68 r ratest: ng

1 1

9

2 5 2 1

37 6

5 3 5

40 4

1 2

2

1 2 1 1

1

1

17 1

35 11

10 1

12

1

6 2

1

8 1

29 14

35 9

14 4

16 30

6 5

2 10

3 3

4

4 11 9 5

2 3 1 14

2 3 1 3

28

2 4 3 2

8

1

4

2

1 1 2 16 56 1 20 9 15 6 1 12 4 1 22 5 46 those failing 1 e tea< her ti s t . TI e

1

1

17 1

6

1 2

4 14

3 3

12 1 1

4

10 1 1 1 2 9 25 1 1 3 1 1 3 1 2 1 1 6 4 nuri a tes' ed on] y thoi e f a i ed by teach« r .

2

4

4 5

16 27

8 36

8 10

17 29

2 9

2 10

29 45

6 7

23 38

1 1

1 2

2

13 11

1

4

3 4

6 8

3 3

3 5

476 50

353 30

123 20

4 1

22 2

33 6

37

10 209

9

5 38

18 22 1 0

113 123 68 19

15 34 1

9 4

2

1

1

62 157

7

16

4 40

18

46

7 7 33

4 5

43 40 2 1

11

1 5

1 1

1 1

1

1

2 16

2 4

1

4 9

2

1 1

1

1 4

3 1

2

358

131

6

3 1

2

1

3

2 2 1 1

515

145 69 19

u M

¡B •S

I

sa

8 1

7 3

5 3

1

1

13 4

3

1 10

12

6

2

1

18

6

1 7 6

11 2 12

1 1

2

1

/,

4 4

&

1

15 15 10

1

- 1954

1

neuRE 22

PART - T E S T S

1955

FAILED

-

s o

u

t¡ D

I

1-1

3

a

1. CLINICAL CRITERIA 2. TEACHER OBSERVATION UNDHt-REFHffiALS REFERRALS FART TESTS TAILED a . Without pertinent ooanent b. Straina to see, squints 0. T i l t s brad d. Syes turn In or out a. Blepharitis, styes f . Syes a i t a r , blinking g. Poor visual acuity h. Holds book oloae 1. Narvoua twitching of eyas 3 . NURSE OBSHtTATIOH UND1R-REFERRALS REFERRALS PART TESTS FAIIJD a . Without pertinent consent b. Strains to see, squints o* Eyes turn in or out d. Blepharitis, styes e . Byes eater, blinking f . Poor visual acuity

249

5

37

47

11

60

25

8

9

5

1

31

7

4 1

24 13

36 11

8 4

31 29

18 7

4 4

6 2

4 1

1

20 11

3 4

13

6 3

1 3

24 3

5 2

3

1

1

1

8 1 1

3

1

1

179

90

160 89

115 39 7 1 5 3 3 4 2

48 26 6 0 3 3 1 2 1

67 13 1 1 2 0 2 2 1

70

16

195 54

57 9 1 1 1 1

12 3 0 0 1 0

45 6 1 1 0 1

4 . STATE RECOWEHDED HtOCEDHOt 182 UNDE8-REFB1RAI3 88 67 21 REFEMUI3 PART TESTS FAIU9 (118) (135) (253) a . Teacher Test 86 103 17 1) Visual acuity 119 33 152 2) +1.50 D. Sphere 17 32 15 3) +2.00 D. Sphere b. Nurse Retest 52 55 3 1) Visual acuity 18 9 9 2) +1.50 D. Sphere 6 8 2 3) +2.00 D. Sphere 11 10 21 It) Worth Dot t e s t Note: All referrals by nurse af' sr retesl lng thosi failing t le The nurse tested only tho a failed by teaehi r . 5. TW.pTMfy.nr.fji UNDHt-REFHIRALS REFHUUIS FART TESTS FAILED a. Simultaneous viaion b. Vertical posture - far c . lateral posture - far d. Fusion - far point e. R.E.Usable vision - far f . L.E.Usable vision - far g. lateral posture - near h. Fusion - near point 1. R.E. Usable vision - near j . L.E. Usable vision - near 6. MODIFIED CLINICAL TECHNIQUE UNDER-REFffiRALS REFERRALS PART TESTS FAILED a . Visual Acuity b. Ski«metry c.. Cover Test d. Inspection for Organic Prob.

31 6

43 4

10 1

38 22

20 5

6 2

7 2

4 1

1

24 7

5 2

1

5 1

2

1

20 2

5

2

1 1

1

1

6 1

1

1 1

1 4 1

27 10

43 4

10 1

34 26

22 3

4 4

3 1

7 11 7

5 6 2

1 1

31 3 3

4 4 2

7

1

4 6 3

4

1

22 2 2 2

2 1 1

4

tea sher t >st.

4 3 1

1 7

2 3

1 1

19 3 1

5 1 1

1

9

3

5

3

1 30

1 6

1 1

5 7 17 14 25 23 14 13 19 18

1 1 1 1 3 6 2 3 2 5

130

7

26 21 20

6 3 2 5

1 3 25 28 26 24 20 17 24 23

1 3 4 6 1 3 2 4

1 1 11 11 48 50 15 13 29 30

2 10 12 11 16 11 7 13 13

1 6 5 7 6 3 3 7 7

2 4 3 4 3 5 2 2

37

47

2 10

2 58

25

8

8

5

1

16 30 10

8 8 45

5 4 2 11

52 49 21

11 16 20

7 2 8

2 3 7 7

2 5 1 4

1

5

142 146 139 31

1 1

2 5

8

5 244

27

1

20 11

1

2 23

1 2 4 4 2 2 3 4

271

5

60

1 1 7 7 23 23 8 10 17 16

10 12 275 268 530 492 284 349 396 388

8 1

4 8

10 17 84 90 160 166 82 80 123 126

20 29 359 358 690 658 366 ¿29 519 514

1

4 1

2 45

19 230

1

1 1

1

6 31

833

14 14 12 0

1

5

1063

156 160 151 31

1

1 2 1 1 1 1

1

1 1 1

1 1

1955

FIGURE

PART - T E S T S

23

FAILED - 1956

a

• as 8