Photorefractive keratectomy and laser in situ keratomileusis for myopia between 6.00 and 10.00 diopters

Abstract

Background: Excimer laser photorefractive keratectomy (PRK) can be effective in correcting myopia up to -6.00 diopters (D). Between -6.00 D and -10.00 D, the procedure is considered less effective and safe because it has been associated with dense scar formation and a high rate of regression. We compared photorefractive keratectomy (PRK) in this group of myopes with excimer laser keratomileusis in situ (LASIK).

Methods: Forty consecutive eyes with a manifest refraction between -6.00 and -10.00 D were treated with PRK using an ablation-zone diameter of 6 mm. Subsequently, 40 consecutive eyes were treated with LASIK under a hinged flap using an ablation-zone diameter of 5 mm. All procedures used a Summit OmniMed laser and were done by the same surgeon.

Results: Preoperatively, 24 eyes (60%) undergoing PRK had 20/20 spectacle-corrected visual acuity; 1 year postoperatively, 20 (50%) had 20/20 vision uncorrected. Preoperatively, 13 eyes (33%) undergoing LASIK had 20/20 spectacle-corrected visual acuity; 1 year postoperatively, 24 (60%) could see 20/20 uncorrected. Sixteen (39%) PRK eyes had a spherical equivalent refraction within +/-1.00 D at 1 year; 20 (60%) eyes undergoing LASIK had a refraction within +/-1.00 D at that point. None of the eyes treated with LASIK developed corneal haze, while after PRK, 36 eyes (90%) developed haze (23 eyes [57%] +2 to +3).

Conclusion: LASIK under a hinged flap proved superior to PRK in treating myopia between -6.00 D and -10.00 D.