Assessing the predictive ability of the test-positive findings of an elementary school vision screening.

Abstract

The purpose of this study is to assess the predictive ability of the test-positive findings of an elementary school vision screening program, conducted by 2nd-year optometry students, in identifying children with eye or vision disorders. A modified version of the Modified Clinical Technique (MCT) vision screening was administered to elementary children from a below-average socioeconomic neighborhood in Houston, Texas. Comprehensive eye and vision examinations were provided to the available children who failed the vision screening. The screening was administered by groups of 2nd-year optometry students with the assistance of a 4th-year optometry student, and supervised by a faculty member licensed to practice optometry. The follow-up examinations were provided by supervised 4th-year optometry students in a clinical setting based at the elementary school. Positive predictive values calculated from the screening and examination findings estimate the probability that a failure on one or more of the screening tests would identify children with eye or vision disorders. Sixty-nine percent of the test-positive children examined were found to be true positives by the criteria developed in a study of vision screening methods in Orinda, California from 1954 through 1956. The predictive ability of this study's test-positive findings for identifying eye and vision disorders was found to be less than the predictive ability of the Orinda Study findings. This reduced predictive ability of the present study resulted in a larger number of children being overreferred for examinations than had occurred in the Orinda Study. The reduction in the ability of the test-positive findings of the current study's screening program to identify accurately children with eye and vision problems is most likely due to the limited experience of the optometry students conducting the screening program. The inability of this retrospective study to evaluate the accuracy of the test-negatives is a major limitation in assessing the total effectiveness of this vision screening program. Although the present study may indicate some value in optometry students conducting elementary vision screening programs, a prospective study which could assess the predictive ability of both test-positive and test-negative findings, as well as determine the sensitivity and specificity of the screening program, is needed to assess more fully the effectiveness of school vision screening programs using professional students.