The Effect of Retinal Cryotherapy on the Refraction in Rabbit Eyes

Khwarg, Sang In; Lim, Key Hwan; Chang, Bong Lean

Abstract

Whether the myopia associated with retinopathy of prematurity (ROP) is influenced by retinal cryotherapy is still controversial. The purpose of this study is to investigate the effects of retinal cryotherapy and retinal photocoagulation on the refraction and refractive components of the eyes of normal immature rabbits. In the 58 pigmented rabbits of 5 weeks old, retinal cryotherapy (360 degrees, 180 degrees) or retinal photocoagulation (360 degrees) were performed to the one eye. And cycloplegic refractions along with the measurements of anterior chamber depth, lens thickness and axial length were performed preoperatively and at postoperative 2, 4, 8, 12, 16 weeks, respectively. The cycloplegic refractions were changed significantly to the hyperopic side and the axial lengths were significantly shorter in the treated eyes as compared with those in the control eyes, postoperatively (p<0.05). In the cryotherapy groups, the amounts of changes for cycloplegic refractions and axial lengths slowly decreased 2 or 4 weeks after treatment, but in the retinal photocoagulation group. those were constant for the whole postoperative period. Comparing the changes between three experimental groups. there was a significant difference between two retinal cryotherapy groups (p<0.05) but not between two retinal cryotherapy groups and retinal photocoagulation group (p>0.05). These results may be a clue which supports partially the opinion that retinal cryotherapy has no unfavorable effect on the myopia associated with ROP.