Modified corneoscleral incision to reduce postoperative astigmatism after 6 mm diameter intraocular lens implantation

Abstract

I modified the corneoscleral incision for cataract surgery so the incision is located between the 9 o'clock and 12 o'clock positions and termed it the BENT incision (abbreviated from "between nine and twelve o'clock"). I made the incision on 110 patients for phacoemulsification and 6.0 mm diameter poly(methyl methacrylate) intraocular lens implantation and analyzed postoperative corneal astigmatism. The results revealed that the surgically induced astigmatism was 0.3 diopters of with-the-rule shift in the early postoperative weeks and remained virtually unchanged for the subsequent 24 weeks. This amount of astigmatism was significantly smaller and more stable than that of the conventional superior incision performed on 59 patients. A more rapid stabilization of astigmatism after the BENT approach resulted in better uncorrected visual acuity in the early postoperative period. These findings suggest that corneal astigmatism after cataract surgery is affected by the mechanical force of eyelids and extraocular muscles. The BENT incision would effectively minimize the wound-stretching forces and result in earlier stabilization of a lesser degree of postoperative corneal astigmatism.