Efficacy and safety of excimer laser photorefractive keratectomy and radial keratotomy for bilateral myopia.

PURPOSE: To compare the safety and efficacy of radial keratotomy (RK) and photorefractive keratectomy (PRK) to correct myopia. METHODS: In this randomized, prospective, parallel-group study, 33 patients with bilateral myopia of 1.00 to 5.00 diopters (D) had PRK in one eye and RK in the other. The order of surgeries and treatment assignments were randomized, and the bilateral surgeries were within 1 week for each patient. Data were collected using standardized procedures. Clinical measurements and satisfaction surveys were taken in masked fashion. RESULTS: Eyes that had PRK had statistically significantly more residual myopia than RK-treated eyes at 3, 6, and 12 months postoperatively. This result was attributed to the use of an older excimer laser PRK algorithm that was used at the initiation of the study. No eye that had PRK was overcorrected by 0.50 D or more at 1 year postoperatively, while seven eyes that had RK were overcorrected by at least 0.50 D and six were overcorrected by 1.00 D. Eyes that had PRK had a statistically significant mean shift in the myopic direction between 6 and 12 months postoperatively; two RK eyes had hyperopic shifts of 1.00 D. Three RK eyes and two PRK eyes failed to achieve an uncorrected visual acuity of 20/40 or better by 12 months postoperatively. No eye lost any best corrected visual acuity. CONCLUSION: The two procedures were comparably safe and effective in treating mild to moderate myopia under this protocol. Eyes that had PRK were somewhat more myopic at 1 year after surgery, attributable to the older PRK ablation algorithm. Adoption of newer (current) laser algorithms has improved the predictability of PRK. There was also evidence of reduced variability of outcome in the PRK group. The PRK eyes did not exhibit hyperopic shifts during the 1 year follow-up.

Cryolathe keratomileusis for correction of myopia of 4.00 to 8.00 diopters.

BACKGROUND: During the last decade, new refractive surgery procedures have been introduced; older techniques have been modified or even abandoned. Cryolathe myopic keratomileusis has been in clinical use for approximately 30 years. In this retrospective study, we present our experience in applying this technique for the correction of 4.00 to 8.00 diopters of myopia. METHODS: Autoplastic cryolathe keratomileusis was performed on 61 eyes of 44 patients who were at least 18 years of age, with a preoperative myopia of 8.00 D or less, and 4.00 D or less of astigmatism. The surgical technique used the Barraquer microkeratome and cryolathe. The mean postoperative observation period was 28 months (range, 12 to 73 months). RESULTS: The mean preoperative spherical equivalent refraction was -5.95 +/- 1.14 D (range, -4.25 to -8.00 D). After a mean follow up of 28 months, the mean postoperative spherical equivalent refraction was -0.91 +/- 1.49 D (range, +2.00 to -7.75 D). At the end of follow up, 37 eyes (60.7%) were within +/- 1.00 D of emmetropia and 44 eyes (72.1%) achieved 20/40 or better uncorrected visual acuity. Complications included corneal ectasia in one eye (1.6%) and epithelial inclusions of the interface in another eye (1.6%). Irregular astigmatism was not a major problem, occurring in only two eyes (3.3%). CONCLUSIONS: Cryolathe keratomileusis is a proven and feasible technique for correcting moderate to high amounts of myopia in properly selected patients; there is a low incidence of vision-threatening complications.

Subepithelial reticular cicatrization following radial keratotomy in a patient with inactive trachoma.

BACKGROUND: Opacification of the clear optical zone following radial keratotomy has not been observed before. METHODS AND RESULTS: The authors noted the appearance of subepithelial dense white reticular cicatrization in the central area following radial keratotomy in a patient with inactive trachoma and clear cornea. The corneal changes resulted in regression of the surgical effect and decrease in visual acuity. A good visual result was obtained by performing homoplastic myopic keratomileusis in situ. Clinical and histopathological findings are presented. CONCLUSIONS: Patients undergoing radial keratotomy should be carefully screened for inactive trachoma which may contribute toward postoperative reticulate opacity of the central cornea.