Excimer laser photorefractive keratectomy for extreme myopia.

PURPOSE: To determine the efficacy, predictability, and safety of excimer laser photorefractive keratectomy (PRK) in treating very high myopia.

SETTING

Laser Vision Harley Street, London, England.

METHODS

Eighty-eight patients whose spherical errors ranged from -6.00 to -20.00 diopters (D) had PRK with the VISX 20/20B excimer laser and a multizone ablation technique. The patients were divided into two groups of 44: those with errors up to -10.00 D and those with errors above -10.25 D. Visual acuity, manifest refraction, corneal haze, and topography were examined 1 week and 1, 2, 3, 6, and 12 months postoperatively.

RESULTS

Minimum follow-up was 1 year. Predictability of results was greater in Group 1 than in Group 2 patients: 90.0% were within 1.00 D of intended correction and 70.0% were within 2.00 D, respectively. The average for both groups was 85.0% within 2.00 D and 63.6% within 1.00 D of intended correction. No serious complications or overcorrections were seen in either group. Preoperative astigmatism ranged from 1.50 to 5.50 D. Postoperatively, 82.0% of patients had no residual astigmatism; in the other 18.0%, it ranged from 0.50 to 2.50 D (83.0% had 1.00 D or less). Results with the multizone technique were more successful than those reported with the single- or dual-zone ablation techniques.

CONCLUSIONS

High myopia was treated with reasonable success using the VISX 20/20B excimer laser system and a multizone technique. Comparable studies using single- and dual-zone approaches appear to have less successful outcomes.