Abstract
Abstract: :
Purpose: Refractive errors are a common cause of amblyopia. In case of an early detection and therapy a permanent reduction in visual acuity can be prevented. The purpose of the present study is to compare the effectiveness of two preschool screening strategies. Methods: 89 children aged 3.5 to 4.5 years were examined under authentic screening conditions in their kindergartens without cycloplegia. The H-test, a modification of the Swedish Kolt test, was used to measure the visual acuity (referral criteria 20/25). Refraction was examined using a handheld autorefractor. The results of objective refraction in cycloplegia were used as references. The necessity of spectacle prescription was defined according to the median responses of a survey of 334 AAPOS members (Miller JM, Harvey EM, 1998). The validity of both strategies is compared. Results: Sensitivity is higher for testing visual acuity (90.0%) than for automated refraction (73.3%). Specificity and positive predictive value are higher for automated refraction (79.7%, 64.7%) than for testing visual acuity (27.1%, 38.6%). The high percentage of false positive results would cause many unnecessary referrals. Conclusions: Screening by testing a single parameter (visual acuity or non-cycloplegic automated refraction) cannot be recommended due to the high rate of false positive results. Alternative strategies are discussed. The present study is supported by the Bertelsmann foundation.
Keywords: amblyopia • refraction • visual development: infancy and childhood