Effect of axis orientation and amount of astigmatism on visual acuity.

Abstract

AIMS: The purpose of the study was to find out the effect of axis orientation and amount of astigmatism on visual acuity.

METHODOLOGY: An informed consent was taken describing the detail of the study and implication; therefore, the subjects were assured of their confidentiality of information and outcome. The sample size was 70 patients. Patients’ visual acuity was taken. After that objective refraction was done with retinoscopy technique. At the end, subjective refraction of patients was done. And the effect of axis orientation of astigmatism (with-the-rule, against-the-rule, or oblique astigmatism) on patient visual acuity was measured.

RESULTS: Most of the patients had with the rule astigmatism; they had good visual acuity as compared to against the rule and oblique astigmatism. The amount of against the rule astigmatism was moderate and visual acuity ranges in 22 patients out of 70 was 6/24-6/60. The amount of astigmatism in with the rule astigmatism was mild and visual acuity ranges in 24 patients out of 70 was 6/9-6/12. The amount of oblique astigmatism was severe and visual acuity ranges in 21 patients out of 70 was 6/18-6/24.

CONCLUSION: Against the rule, astigmatism affects the visual acuity more as compared to with the rule and oblique astigmatism.