Treatment of hyperopia with contact Ho : YAG laser thermal keratoplasty

PURPOSE: To evaluate the effectiveness, safety, and stability of contact Ho :YAG laser thermal keratoplasty for low to moderate hyperopia. METHODS: Fifty-five hyperopic eyes of 39 patients were treated with a Techn omed contact Ho:YAC: laser; 23 eyes were treated a second time. Treatment p arameters were 1 octagonal ring of 8 spots with a treatment diameter of 6 m m, 7 mm, or 8 mm, Efficacy of the Ho:YAG laser treatment was evaluated afte r 6 months, comparing 3 treatment zone diameters. Stability and efficacy af ter 12 months was evaluated comparing 7-mm and 8-mm treatment zone diameter s. RESULTS: Mean reduction of spherical equivalent refraction after 6 months w as not statistically significantly different between the 6-mm or 7-mm diame ter zones: 1.42 (+/-1.30) D versus 2.22 (+/-0.44) D, An 8-mm diameter treat ment zone was significantly less effective, 1.12 (+/-0.47) D. Longer follow -up did not show stability: mean reduction of spherical equivalent manifest refraction was 1.58 (+/-0.45) D for the 7-mm diameter treatment zone and 0 .82 (+/-0.61) D for the 8-mm diameter treatment zone after approximately 12 months. Retreatment had a limited additive effect. No clinically significa nt loss of spectacle-corrected visual acuity was reported. No eyes lost mor e than 1 line of visual acuity. CONCLUSION: Contact Ho:YAG: laser thermal keratoplasty corrected hyperopia up to 2.50 D, but predictability was poor and a regression of initial effec t occurred. Instability of refraction persisted to 1 year after surgery.