CORNEAL ASTIGMATISM INDUCED BY SUPERIOR VERSUS TEMPORAL CORNEAL INCISIONS FOR EXTRACAPSULAR CATARACT-EXTRACTION

Purpose: We tested the hypothesis that superior corneal sections induce a shift to 'against-the-rule' astigmatism and temporal corneal sections lead to the preferred 'with-the-rule' astigmatism. Methods: We conducted a prospective randomised trial of superior versus temporal corneal incisions in extracapsular cataract surgery in a hospital practice. Thirty nine eyes of 37 patients were included. The induced astigmatism was analysed by three methods. Results: When analysed by Cravy's method of induced astigmatic cylinders, the superior incision induced a greater degree of 'with-the-rule' astigmatic cylinder prior to sutures removal on day 77 (P<0.049). Long term, the temporal incision produced 1.44 dioptre of 'with-the-rule' astigmatism, while the superior section produced 0.08 dioptre of 'against-the-rule' astigmatism (P<0.001). Conclusion: The results of this small trial indicates that the superior corneal incision produces significantly less astigmatism than the temporal incision. The temporal incision induces a moderate degree of 'with-the-rule' astigmatism.