Excimer laser photorefractive keratectomy for extreme myopia

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

Laser Vision Harley Street, London, England.

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.

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.

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.