Automated in situ keratomileusis for myopia

BACKGROUND: In situ keratomileusis is a rapidly changing refractive corneal surgical procedure for the correction of myopia. We report hero the results of a retrospective study of in situ keratomileusis with the refractive cut made with a microkeratome. The technique represents an intermediate stage of development that used a sutured corneal disc, an early automated microkeratome, and no reoperations for residual refractive error. METHODS: We carried out a retrospective chart review of the first 107 consecutive eyes (73 patients) that received in situ keratomileusis with an automated microkeratome (Ruiz corneal shaper) at the El Maghraby Hospital in Jeddah, Saudi Arabia between November, 1991 and February, 1993. Sixty-three eyes (59%) were followed for a mean of 1 year. Manifest refraction measured by an ophthalmologist or optometrist was the major response variable. Surgery followed the Ruiz homogram, which specified an anterior corneal disc approximately 7.2 mm in diameter and 160 μm in thickness and a plano in situ refractive cut a mean of 4.2 mm in diameter and 93 μm in thickness. RESULTS: The mean baseline spherical equivalent of the manifest refraction was - 11.97±5.30 diopters (D) (range, -3.75 to -28.00 D). At a mean of 1 year after surgery, the mean refraction was -1.86±3.13 D (range, -13.25 to +4.63 D); 13 eyes (21%) had a refraction within ±0.50 D and 22 (35%) within ±1.00 D. Undercorrection of more than -1.00 D was present in 36 eyes (57%). At baseline, 48 of 63 eyes (75%) could see 20/40 or better with spectacle correction. At 1 year, 13 of 63 eyes (21%) could see 20/40 or better uncorrected. To measure the stability of refraction in 61 eyes, the mean refraction at 1 month of +0.62±2.43 D was compared to that at 1 year after surgery (mean, -1.41±3.10 D), indicating a loss of effect in the direction of increasing myopia. Nine eyes (14%) lost two to five lines of spectacle- corrected visual acuity. Two eyes had central epithelial implantation plaques in the lamellar bed that required removal. CONCLUSION: In situ keratomileusis using an automated corneal shaper and sutured corneal discs at an intermediate stage of development produced less than desirable refractive and visual acuity results.