Benefit of against-the-rule astigmatism to uncorrected near acuity.

ABSTRACT

PURPOSE: To determine whether with-the-rule (WTR) or against-the-rule (ATR) astigmatism gives a better visual outcome after cataract and intraocular lens (IOL) implantation surgery by comparing the uncorrected distance and near visual acuities in eyes with low, simple, myopic residual astigmatism. SETTING: S. Geraldo Eye Hospital, Federal University of Minas Gerais, Belo Horizonte, Brazil. METHODS: Two groups of 10 eyes each, one with WTR and the other with ATR simple, myopic astigmatism, were studied after uneventful cataract and IOL implantation surgery. All patients had an uncorrected distance visual acuity of 20/40 or better. The negative cylinder ranged from 1.00 to 1.50 diopters (D). The uncorrected distance and near visual acuities of the two groups were compared. RESULTS: There was no statistically significant between-group difference in uncorrected distance visual acuity. However, for uncorrected near, the difference between groups was highly statistically significant (P < .001). Patients with ATR astigmatism had much better uncorrected near acuity than those with WTR astigmatism. CONCLUSION: In pseudophakia, low, simple, ATR myopic astigmatism is better than WTR astigmatism because it provides superior uncorrected near visual acuity.