Photorefractive keratectomy for undercorrected myopia after radial keratotomy: two-year follow up

We evaluated the clinical results of excimer laser photorefractive keratectomy (PRK) on 18 myopic eyes of 13 patients with residual myopia after radial keratotomy. Follow up was 24 months or more and the time interval between radial keratotomy and PRK ranged from 12 to 94 months. Patients were divided into two groups for analysis based on their preoperative myopia: group 1 (-6.00 diopters (D) or less), group 2 (more than -6.00 D). Uncorrected visual acuity at 2 years follow up was 20/40 or better in 86% (group 1) and 50% (group 2). Mean manifest refractive change was from -3.55 D to -0.91 D in group 1 and from -7.44 D to -2.50 D in group 2. Predictability within 1.00 D between attempted and achieved correction was 71.4% (group 1) and 80% (group 2). Most complications were transient except decreased spectacle corrected visual acuity in one eye--a complication also reported by others. Glare (61%) and decreased vision at night (50%) were the most troublesome subjective symptoms. These results show that previous radial keratotomy may not influence the myopic correction of PRK. Planned two-stage myopic correction (PRK after radial keratotomy) in high myopia can be considered a useful technique.