2-INCISION RADIAL KERATOTOMY FOR LOW MYOPIA WITH ASTIGMATISM

Purpose: To evaluate the effectiveness of two-incision radial keratoto my (RK) in correcting low-magnitude refractive myopic astigmatism. Set ting: Two clinical study sites, one in St. Louis, Missouri, USA, the o ther in Caracas, Venezuela. Methods: Fifty-seven eyes of 43 patients w ith low-magnitude myopic astigmatism had two-incision RK at one of two clinical study sites. In the initial phase of this series, 10 eyes wi th amblyopia at the 20/30 level had surgery at one center. Refractive keratotomy was performed with the radial incision placed in the plus c ylinder axis of refraction. This axis was verified as the meridian of greatest corneal curvature by standard keratometry and computer-assist ed corneal topographic analysis. Two eyes received a second operation (enhancement).Results: Mean follow-up was 11.1 months (range 6 to 12 m onths). Mean preoperative and postoperative myopic spherical equivalen t measured -1.42 diopters (D) +/- 0.51 (SD) and -0.14 +/- 0.39 D, resp ectively; the mean reduction was 1.28 +/- 0.59 D (P = .0001). Mean pre operative and postoperative refractive astigmatism was 1.41 +/- 0.45 D and 0.48 +/- 0.33 D, respectively (P = .0001). Mean preoperative and postoperative keratometric astigmatism was 1.26 +/- 0.54 D and 0.31 +/ - 0.35 D, respectively, a mean reduction of 0.95 D (P = .0001). The su rgical meridian was flattened by an average of 2.06 D by keratometry a nd the orthogonal meridian, by an average of 1.10 D. Preoperative unco rrected visual acuity (UCVA) was 20/40 or better in five (9%) eyes (ra nge counting fingers to 20/40). Postoperative UCVA acuity was 20/40 or better in all eyes (mean acuity 20/25). In the nonamblyopic subgroup, mean postoperative UCVA was 20/24. Conclusions: A limited number of r adial incisions placed in the topographically confirmed axis of greate st curvature are effective in the treatment of low-magnitude myopic as tigmatism.