Keratometric comparison of 4.0 mm and 5.5 mm scleral tunnel cataract incisions.

Postoperative keratometric astigmatism was analyzed in 276 consecutive cases of phacoemulsification and posterior chamber lens implantation performed by one surgeon. The series was divided into two groups: one received 4.0 mm incisions and the other 5.5 mm incisions. Incision design was triplanar and required suture closure, i.e., all wounds were closed with two X-pattern 10-0 nylon sutures. Using the Cravy method, an insignificant difference in induced astigmatism was found between the groups at one day, two weeks, and one year after surgery. The average induced diopters of astigmatism for the 4.0 mm group was +0.80 +/- 0.94 at one day, +0.49 +/- 0.73 at two weeks, and -0.34 +/- 0.91 at one year; for the 5.5 mm group it was +0.69 +/- 1.07 at one day, +0.41 +/- 0.85 at two weeks, and -0.23 +/- 1.01 at one year. Two-week uncorrected visual acuity of 20/40 or better was similar for both groups. Seventy-six percent of the 4.0 mm group and 68% of the 5.5 mm group had acuities of 20/40 or better. A significant difference in the incidence of immediate postoperative hyphema was noted. The overall hyphema incidence was 9%, with a 14% and 4% incidence for 5.5 mm and 4.0 mm incisions, respectively.