The Effect Of Astigmatic Blur On Stereopsis

Abstract

Purpose: : To determine the effect of astigmatic blur on stereopsis and whether this is dependent on the axis of the astigmatism at near ( 40 cm ) and distance ( 6 m ) .

Methods: : Astigmatic blur was induced in fourteen healthy subjects ( mean age; 22.5 years, mean spherical equivalent; - 2.92 D ) using plus cylinder lens ( + 0.5 D to + 3.0D ) for orientation control. Horizontal, vertical, and oblique ( 45 ° × left eye and 45 °× right eye ) astigmatism was induced with three binocular axis steps. Stereopsis was recorded at near and distance using OPTEC 6500 Vision Tester^® ( Stereo Optical, Inc. ) .

Results: : Stereopsis degraded with increasing astigmatic blur at near and distance. At distance, with-the-rule astigmatism had the least effect ( p < 0.05 ). There were no significant differences between the three orientations at near stereopsis. The effect of astigmatic blur on stereopsis at near is less than that at distance ( p < 0.01 ).

Conclusions: : The effect of astigmatic blur on stereopsis depended on the axis of the astigmatism and examination distance.

Keywords: binocular vision/stereopsis • astigmatism • perception