The purpose of this study was to compare changes in higher-order aberrations after superior-incision cataract surgery between eyes with a within-the-rule (WTR) astigmatism and an against-the-rule (ATR) astigmatism in patients with positive vertical coma.

This study included patients who presented with positive vertical coma and who underwent cataract surgery through a 2.5 mm superior clear corneal incision. The eyes included in this study were divided into two groups (37 eyes with WTR astigmatism and 33 eyes with ATR astigmatism), and uncorrected visual acuity, best corrected visual acuity, and corneal astigmatism were measured before and after surgery. In addition, anterior, posterior, and total aberrations (i.e., oblique trefoil, horizontal trefoil, vertical coma, horizontal coma, spherical aberration, and total higher-order aberrations) were measured using a Pentacam.

In the WTR astigmatism group, anterior/posterior corneal aberrations and total aberrations were significantly decreased after surgery ( p < 0.05). However, in the ATR astigmatism group, a significant decrease in the posterior vertical coma ( p = 0.008) was observed, although there was no change in total vertical coma. A significant increase in oblique trefoil was observed in both groups, while a significant decrease in horizontal trefoil was found in the ATR astigmatism group (all p < 0.05). For spherical aberration, the ATR astigmatism group showed a significant decrease in anterior cornea aberrations ( p < 0.001). For total higher-order aberrations, the WTR astigmatism group showed a significant increase in anterior and posterior aberrations, while the ATR astigmatism group showed a significant increase in posterior aberrations ( p < 0.05, p = 0.001, respectively). In the case of horizontal coma and corneal astigmatism, both groups exhibited no significant changes after surgery.

When superior-incision cataract surgery was performed, vertical coma was affected by the axis of astigmatism, resulting in a significant decrease in the WTR astigmatism group. However, no significant changes in corneal astigmatism were observed before and after surgery.