[Vision test device: possibilities and limits of LCD technique].

Abstract

An automatic visual acuity test examining visual acuity at 5 m distance is presented. An LCD screen with 400 x 640 pixel is used for graphic display. The Landolt rings are selected randomly. The test presented here complies well with the criteria of DIN 58220. Accuracy estimates for representation of the Landolt rings in raster graphics are discussed. With the method suggested, the testing of visual acuity, one of the most important tests in ophthalmological practice, is simplified and its reliability and results are improved. The method allows tests at short time intervals to trace the time dependency of visual acuity. Furthermore, the test may be delegated to support personnel.