Long-term results of excimer laser corneal surface ablation for correction of myopia and astigmatism in suspected keratoconus

Abstract

Objective To explore the long-term safety, efficacy and stability of laser epithelial keratomileusis (LASEK) and epipolis laser in situ keratomileusis (Epi-LASIK) for the correction of myopia and astigmatism in suspected keratoconus. Methods This was a retrospective clinical study.Thirty-eight patients with 55 eyes suspected to have keratoconus were enrolled in the study. All eyes were myopic, ranging from -3.25 to -7.75 D [(-5.54±2.18) D], cylinder 0 to 3 D[(0.80±0.75)D],with a central corneal thickness of 479 to 605 μm, and stage one keratoconus (KC1) detected by keratography. Refraction and keratograph were stable for at least 2 years in all eyes. Fifty-five eyes successfully underwent either LASEK (38 eyes) or Epi-LASIK (17 eyes). Visual acuity, refraction,and keratograph were checked postoperatively from 6 months to more than 2 years (2 to 5 years).A paired samples t test (normal distribution) and a Wilcoxon Signed Ranks test (non-normal distribution)were used to compare the data before and after surgery. Results More than 2 years postoperatively,uncorrected visual acuity was 1.0 or better in 48 eyes (87.3%), the efficacy index was 1.002; best spectacle-corrected visual acuity remained unchanged or improved in 51 eyes (92.7%), and one line was lost in 4 eyes (7.3%), the safety index was 1.053. Mean spherical equivalent refraction was (-0.11±0.45) D; spherical equivalent refraction was within ±0.50 D in 49 eyes (89.1%) and within ±1.00 D in 53 eyes (96.4%). Myopic refraction and astigmatism more than 2 years postoperatively were not significantly different from 6 months postoperatively (P＞0.05). Mean keratoconus index was 1.08±0.01 preoperatively and 1.02±0.04 more than 2 years postoperatively (Z=-6.098, P＜0.01). There was no obvious haze or keratoeonus progression during the follow-up period. Conclusion Patient's age, myopic refraction, corneal thickness and stability of refraction and keratograph are the key points to determine whether suspected cases of keratoconus can undergo LASEK or Epi-LASIK.LASEK and Epi-LASIK seem to be safe and effective procedures for reducing or eliminating myopia and astigmatism in suspected keratoconus with stable refraction and keratograph. More monitoring is needed to prove long-term safety. Key words: Keratoconus; Photorefractive keratectomy; Myopia; Astigmatism; Corneal topography