Correlation between stereoacuity and induced astigmatism: a prospective study

Abstract

Background and Aim: Stereopsis represents the highest grade of Binocular Single Vision wherein two dissimilar images of the same object are formed, simultaneously, at the maculae of the two eyes, and these images are then processed in the visual cortex to produce a single fused image, whose location in space can be perceived. Material and Methods: Present Randomized, Prospective, Comparative, study was performed at Department of Ophthalmology Bharati Hospital & Research Centre, Pune. Two thousand subjects were divided into two groups, they were divided into 2 groups using randomized table. Group 1 was subjected to binocular induced astigmatism. Group 2 was subjected to monocular induced astigmatism. Binocular Induced Astigmatism was induced in two groups, (500 participants in each group) either Myopic Astigmatism or Hypermetropic Astigmatism, similarly Monocular was further subdivided in to two groups (500 participants in each group): Myopic Astigmatism and Hypermetropic Astigmatism. Results: With both +1 Dcyl & +2 Dcyl binocular induced myopic astigmatism, stereoacuity was affected maximum at 45 and least affected at 180. With both -1 Dcyl & -2 Dcyl binocular induced hypermetropic astigmatism, stereoacuity was affected maximum at 45 and least affected at 180. Stereoacuity in binocular induced hypermetropic astigmatism was more affected than binocular induced myopic astigmatism. Stereoauity was grossly affected in both monocular myopic and hypermetropic astigmatism. With the rule astigmatism had remarkable difference in stereoacuity in both myopic and hypermetropic induced astigmatism of 1 and 2 diopters cylinders. Stereoacuity was more affected in hypermetropic group. Conclusion: Stereoacuity is most affected at oblique axis (450). There is gross reduction in stereoacuity in induced monocular astigmatism than binocular astigmatism. Both myopic and hypermetropic against the rule astigmatism has comparable deterioration of stereoacuity.