Enlargement of the temporal clear corneal cataract incision to treat pre-existing astigmatism

PURPOSE: To evaluate the effect of enlarging the temporal clear corneal cataract incision on pre-existing against-the-rule astigmatism. METHODS: We performed a prospective study of 21 eyes of 21 consecutive patients with astigmatism greater > or = 1.75 D, who underwent temporal clear corneal cataract surgery by phacoemulsification. Patients were divided into two groups. The first group, with medium astigmatism, consisted of 14 patients (14 eyes) with 1.75 to 2.74 D of against-the-rule astigmatism, and had an incision enlarged to 4.5 mm. The second group, with higher astigmatism, consisted of seven patients (seven eyes) with 2.75 to 3.75 D of against-the-rule astigmatism and had an incision enlarged to 5.5 mm. Corneal topography was performed preoperatively and 24 months postoperatively on all eyes. Surgically induced cylinder changes were compared by examining preoperative and postoperative keratometric power using vector analysis. RESULTS: Mean preoperative cylinder in the medium against-the-rule astigmatism group was 2.10 +/- 0.23 D and mean postoperative cylinder at 3 months was 1.17 +/- 0.29 D. Using vector analysis, mean change in cylinder in the medium group was 0.93 +/- 0.42 D (P < .001). In the higher against-the-rule astigmatism group, mean preoperative cylinder was 2.85 +/- 0.10 D and mean postoperative cylinder at 3 months was 1.63 +/- 0.38 D. Mean change in cylinder in the higher astigmatism group was 1.34 +/- 0.58 D (P < .001). For both groups, Student's t-test showed that the postoperative decrease in cylinder was statistically significant (P = .005). CONCLUSION: By enlarging the size of the standard (2.8 to 3.5 mm) temporal clear corneal cataract incision, pre-existing against-the-rule astigmatism was reduced.