The Effect of Holmium:YAG Laser Thermokeratoplasty on Corneal Astigmatism in Rabbits

ABSTRACT

This animal study was conducted to investigate the effect of holmium:YAG laser thermokeratoplasty on correction of hyperopic astigmatism. A pulsed holmium:YAG laser emitting a wavelength of 2.06 micrometer was used. Arcuate, reverse arcuate, linear patterns of laser burn were applied along the flat corneal meridian and their effects on the rabbit corneal curvature were studied. Keratometric measurements and cycloplegic refractive error were determined preoperatively, one, two, and three months after operation. The changes of refractive astigmatism in three patterns of laser burn were 0.8130, 3.0243, 0.8437 diopter, respectively, compared to that of the control group on postoperative three months. The changes of keratometric astigmatism were 1.1719, 3.0737, 0.7812 diopter, respectively, compared to that of the control group on postoperative three months. We found that holmium:YAG laser thermokeratoplasty is effective in steepening flat corneal meridian, and the most effective pattern is reverse arcuate type. In future holmium:YAG laser thermokeratoplasty might be clinically applicable as a operation of hyperopic astigmatism correction.