Phototherapeutic Keratectomy for Granular Corneal Dystrophy

ABSTRACT

PURPOSE: In this study, we evaluated the results of PTK(phototherapeutic keratectomy) for granular corneal dystrophy. METHODS: 5 eyes (4 patients) with granular corneal dystrophy were treated by PTK using Summit ExiMed UV200 and VSIX Star excimer laser systems. The epithelium was removed mechanically with a surgical blade. We used methylcellulose 1.0% as a surface modulator before laser ablation. Focal ablations of the central cornea with an ablation zone of 6.0 mm were performed. Mean ablation depth was 105 +/- 15.81 micrometer (range; 80~120 micrometer) Additional hyperopic PRK was performed on 4 eyes out of 5 eyes at the corneal mid-periphery up to maximum +5.00 D to prevent post-PTK hyperopic shift. Mean follow up period was 54.4 +/- 23.43months (range; 24~84months). RESULTS: Removal of corneal opacities allowed for improvement in both uncorrected visual acuity and best corrected visual acuity in all patients. There was an improvement in best-corrected visual acuity of a mean of 2.6 lines on the Snellen chart. Mean corneal thickness in the area of pathology decreased from 490.5 micrometer before surgery to 391.5 micrometer after surgery. There was a hyperopic shift in all the eyes in spite of additional hyperopic PRK by a mean of +2.44 +/- 0.99 D. There was mild recurrent dystrophic change in an eye but not significant enough to affect visual acuity during the follow up period. No major complications developed in any patients. CONCLUSIONS: Our results suggest that PTK is a safe and effective alternative to penetrating and lamellar keratoplasty in patients with granular corneal dystrophy. Mild post-PTK hyperopic shift occurred in all patients in spite of combined hyperopic PRK up to maximum +5.00 D correction at the corneal mid- peripheral zone according to the refractive powers.