Radial Keratotomy Clear Zone Diameter Errors

Abstract

PURPOSE: To examine the variability of achieved clear zone diameters following radial keratotomy and to determine if refractive outcomes are correlated to clear zone diameter errors. METHODS: Twenty-six patients with radial keratotomy (51 eyes) were studied retrospectively. The central clear zone diameter for each radial incision meridian was measured using a slit-lamp and a photograph. The achieved clear zone diameters were statistically compared to the intended clear zone sizes and to the refractive outcomes. RESULTS: Twenty-nine of the 51 eyes met various exclusion criteria. Ninety individual slit-lamp clear zone measurements were obtained for the remaining 22 eyes. Sixty-two of 90 (69%) achieved clear zone diameters were more than 0.25 mm different than the intended clear zone size. A maximum difference of ±0.80 mm from the intended clear zone marker size was observed. The average clear zone diameter error did not statistically differ between the three refractive outcome groups (undercorrection, emmetropia, and overcorrection). CONCLUSIONS: In selected cases of centripetal radial keratotomy, the achieved clear zone diameter can vary widely from the intended clear zone size despite extensive surgeon experience. [J Refract Surg 1998;14:623-630]