Non-contact holmium:YAG laser thermal keratoplasty for treatment of hyperopia. 18-month follow-up of the U.S. phase IIa clinical trial

Purpose. To assess the safety and efficacy of holmium:YAG laser thermal keratoplasty (Ho:YAG LTK) for the correction of hyperopia. Methods. We report the 18-month follow-up on sighted eyes treated in the Sunrise U.S. Phase IIa clinical study. 18/8 eyes of 18/8 patients were treated with 1/2 rings of 8 laser spots per ring on 6/6 + 7 mm ring diameters using ten laser pulses per ring with variable pulse energies in the range 208 to 242 mJ. Results. At 18 months post-treatment, mean changes in subjective manifest refraction were -0.49/-1.54 D for 13/6 eyes in the 1/2 ring groups. Regressions were 0.05/0.10 D from the 12-month follow-up changes. Mean uncorrected distance visual acuities improved from 0.30/0.15 (ca. 20/70 and 20/125) to 0.49/0.34 (ca. 20/40 and 20/60). No eyes lost more than one line of best spectacle-corrected visual acuity. The mean endothelial cell densities were unchanged. Conclusions. Ho:YAG LTK is a safe and effective treatment for low hyperopia. Two rings of treatment spots produce considerably more refractive correction than one ring.