Astigmatism after small incision cataract surgery. A prospective, randomized, multicenter comparison of 4- and 6.5-mm incisions.

Four surgeons evaluated induced astigmatism and postoperative wound stability in a randomized prospective study of 130 patients undergoing cataract extraction. After phacoemulsification through a scleral pocket, patients received either a 6.5-mm diameter silicone optic posterior chamber intraocular lens (PC IOL) folded for insertion through a 4-mm small incision or a 6.0-mm diameter polymethylmethacrylate (PMMA) optic PC IOL placed through an approximately 6.5-mm conventional incision. Vector analysis calculations of prism diopters (D) of mean postoperative-induced keratometric astigmatism for the small incision versus conventional incision groups were, at day 1, 1.54 D versus 3.07 D (P less than 0.0001); at weeks 1 to 2, 1.00 D versus 2.43 D (P less than 0.0001); at 1 month, 0.98 D versus 1.44 D (P = 0.004); and at 3 months, 0.82 D versus 1.03 D (P = 0.089). Subgroup analysis of the suturing technique for the 6.5-mm incision showed that the technique of wound closure, as well as the wound size, influenced the induced astigmatism. For all four surgeons using three methods of suturing the 6.5-mm wound, however, the variability in the amount of induced cylinder was least with the 4.0-mm wound closed with a horizontal mattress suture. Complications in the two groups were comparable.