A validation study of the vision test battery used in the Health Examination Survey of 1966-1970 was conducted among 210 youths 12-17 years-old who had been part of the larger survey. The study was designed to discover the degree of correspondence between survey test results and clinical examination by an opthalmologist in determining the incidence of myopia and lateral heterophoria. Findings indicated that survey test results for lateral phoria provide reliable estimates of the prevalence of significant esophoria and exophoria among the youth population. The trial lens test for myopia found to give a better estimate of best corrected acuity than tests using present glasses compared to strength of correction needed. Incidence estimates for youths requiring simple spherical lenses were expected to be more accurate than incidence estimates for youths requiring a more complex corrective lens. The major portion of the document consists of tables detailing survey and clinical examination results. (DB)