Theffect of redued binocular visual Acuitt on stereoacuity

Abstract

Abstract This study investigated the effect of optical blur (defocus) on stereoacuity measured by Titmus stereotest. 1n 60 subjects (30 males and 30 females) with nomqal visual acuity and demonstrated near stereoacuity of 40 seconds of arc. Ages enrolled were from 18 to 36 years. The subjects were selected randomly from Faculty of Optometry and Visual Science Clinic (In Khartoum). All subjects were enrolled in the experiment, in which the visual acuity of each subject was blurred (positive and negative blur was conducted), by (1,2 and 3D.Sph) lenses first binocularly and second monocularly, then the stereoacuity was measured by using Titmus stereotest. The drop of stereoacuity was found to be greater with monocular than binocular blur. The average drops due to binocular blur were found to be 49.7 seconds (of arc) with -1.00 D.Sph, 54.2 seconds with -2.00 D.Sph, 189.2 seconds. with -3.00 D.Sph, 50 seconds with +1.00 D.Sph, 260.8 seconds with +2.00 D.Sph and 2180.3 seconds with +3.00 D.Sph. The average drops of monocular blur were 143.8 seconds with —1.00 D.Sph, 1333.7 seconds with —2.00 D.Sph, 2712.3 seconds with -3.00 D.Sph, 92.2 seconds with +1.00 D.Sph, 1701.7 seconds with +2.00 D.Sph and 3000 seconds with +3.00 D.Sph. From this study the positive optical blur was found to cause more drop in the sterescopic acuity than negative optical blur. Key words: Visual acuity, binocular vision, stereoacuity, optical blurs.