Three Years Experience with Radial Keratotomy: The UCLA Study

Abstract

A clinical trial of radial keratotomy was begun under a strict research protocol at the Jules Stein Eye Institute in November 1979. The results after two years of 16-incision keratotomies, as well as more recent eight-incision keratotomies, are reported. The difficulties in obtaining patient compliance at two years is presented and discussed. Thirty-seven eyes (46%) were unavailable for independent examination at two years, and 28 eyes (35%) were not available at all. Of those eyes available for evaluation (16-incision), the mean follow-up was 24.7 (±2) months (range 21–30 months). The mean preoperative myopia for these 52 eyes was −5.20 (±2.11) diopters (D) (range −2.00/−13.50 D), and the mean decrease in myopia was 3.85 (±2.08) D with 50% maintaining an uncorrected visual acuity of 20/40 or better and 33% achieving 20/200 or worse. Uncorrected acuity results were far superior for those patients with preoperative myopia of 5.00 D or less. Two-year central endothelial cell counts on 46 eyes resulted in a +2.0% (±4.3) change in cell density compared with the cell count taken three months after surgery. It appears that long-term endothelial cell loss does not occur. Fourteen eyes (33%) retained a hyperopic cycloplegic refractive error at two years, with four eyes ranging from +2.50 to +5.75 D; thus, this result represents a major complication of 16-incision (3.0 mm optical zone) keratotomy. The microperforation rate of 19% has led to no adverse developments to date. A moratorium from January to June 1981 allowed for evaluation of our results and a change in the protocol to eight-incision keratotomy on patients with less than 6.00 D of myopia and less than 2.00 D of astigmatism. Since that time 63 eyes were operated with a mean follow-up of 9.4 (±6) months (range 2–21 months). The mean preoperative myopia for these eyes was −3.84 (±1.04) D (range −2.00/−6.75 D), and the mean decrease in myopia was 2.85 (±1.05) D, with 65% obtaining an uncorrected visual acuity of 20/40 or better, 13% achieving 20/200 or worse. This was superior to the results with 16-incision keratotomy because of patient selection. Eight-incision surgery achieved 73% of the myopia change achieved with 16-incision surgery. No microperforation occurred in the 62 eyes of the eight-incision series. The complications of glare and variable vision were much less in the eight-incision series than in the 16-incision series, although admittedly based on shorter follow-up. Central endothelial cell counts were obtained in 16 eyes of the eight-incision series at six months after surgery. A mean cell loss of −2.6% (±10.0) was noted that is much less than the 10% loss noted in our three-month evaluation of the 16-incision procedure. The eight-incision surgery lowered the severity of overcorrection myopia dramatically. Thirteen eyes (21%) fell in this range with no eye greater than +2.00 D. While the rate of overcorrection was 29% (15 of 52 eyes) with 16-incision keratotomy and not statistically different (<i>P</i> > 0.7), two eyes were over +4.00 D. One case of incisional bacterial corneal ulcer was treated successfully, leaving a stromal scar and 20/20 unaided acuity. An analysis showed that results were quite similar for three different surgeons.