Abstract

P 019

Brückner Test in unilateral astigmatism

Jung A., Gräf M.
Department of Ophthalmology, University of Gießen

Objective: The Brückner reflex is an easy and quick method to detect amblyogenic factors by an abnormal pupillary red reflex. Usually the test is performed at a distance of 1 m. Because of the divergent optical path of the reflected light, both hypermetropia and myopia should cause a dimming of the red reflex increasing with the test distance from the eye or from the far point of the eye, respectively. In this study, the sensitivity of the Brückner reflex to detect unilateral astigmatism was investigated with regard to the test distance.
Methods: Five experienced observers performed the test at distances of 1 m and 4 m in 5 emmetropic subjects. Unilateral hypermetropic astigmatism with the rule was simulated by cylindrical lenses of -1, -2, -3, -4 diopters which were placed in an unpredictable order in front of both the right and the left eye. Additionally, there were 4 control conditions in each subject with a plano lens in front of both eyes. The same procedure was repeated inducing astigmatism against the rule and both astigmatism with and against the rule with cylindrical lenses of +1, +2, +3 und +4 diopters. The test was defined to be positive, if there was a difference between the red reflexes of both eyes.
Results: At 1 m, hypermetropic astigmatism with (against) the rule of 1, 2, 3 and 4 diopters was detected in 44% (44%), 58% (60%), 76% (66%), and 88% (72%). Myopic astigmatism with (against) the rule was detected in 50% (22%), 60% (48%), 60% (70%), and 70% (80%). At 4 m, hypermetropic astigmatism with (against) the rule of 1, 2, 3 and 4 diopters was detected in 62% (46%), 88% (72%), 100% (82%), and 100% (100%). Myopic astigmatism with (against) the rule was detected in 44% (74%), 74% (98%), 86% (100%), and 92% (100%). Of 400 emmetropic controls, 5.5% and 5.25% were false positive at 1 m and 4 m, respectively.
Conclusions: The Brückner reflex was more sensitive to detect unilateral astigmatism at 4 m than at 1 m distance.

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