Effect of induced astigmatism through cylindrical lenses on stereoacuity

Abstract

Objective: This study was conducted to determine the effect of induced astigmatism through cylindrical lenses on stereoacuity.

Methods: This interventional pre-post study recruited 57 participants of either gender, between the ages of 7 and 40 years in Shalamar Hospital, Lahore, Pakistan. Only emmetropic participants arriving at the Eye Out-patient department of Shalamar Hospital were recruited. TNO test was used for quantification of stereoacuity. Astigmatism was experimentally induced using trail cylindrical lenses of power ±1.00, ±2.00 and ±3.00 Dcyl at the various axis (180°, 135° and 90°). TNO test was again used to measure the change in stereoacuity induced by these trail cylindrical lenses. Wilcoxon signed ranked test was used for the statistical analysis of the data.

Results: Mean baseline stereoacuity ± standard deviation was 61.05±7.947. The highest deterioration in stereoacuity was observed at 135°, followed by 90° and 180°. Higher the dioptric power, the more the deterioration of stereoacuity was observed (p<0.05). Experimentally induced binocular hypermetropic astigmatism deteriorated stereoacuity more than experimentally induced binocular myopic astigmatism.

Conclusion: This study suggests that stereoacuity significantly deteriorates when cylindrical lenses (especially lenses that induce hypermetropic astigmatism) are used. Axis of cylindrical lenses plays an important role in determining the severity of deterioration in stereoacuity.