Effects of Transscleral Cryotherapy and Diathermy on the Ocular Growth in Rabbits

Purpose. To determine the effect of transscleral cryotherapy of diathermy on anterior part of eyeball on ocular growth. Methods. Twenty-four New Zealand White rabbits were used. Transscleral cryotherapy (n=12) or diathermy (n=12) was performed on the right eye of 3-4 weeks old rabbits, the left eye was left untreated for control. Transcleral cryotherapy and diathermy were applied 360° to the retina anterior to the equator, except in areas where the long ciliary arteries and nerves were located. Biometric ocular dimensions (anterior chamber depth, lens thickness, axial length) and intraocular pressure. (IOP) were measured before and then every month until 3 months later. Results. The ocular size of diathermy-treated eyes was significantly smaller than the untreated control eyes from first to third month later (p＜0.01). As well, the size of cryotherapy-treated eye was also smaller than control eye, but it was not significantly different on the first and third month (p=0.17). The anterior chamber depth, lens thickness and IOP were not significantly different between treated and untreated eyes. Histological evidence showed the sclera of diathermy area was thinner than the normal sclera, but the cryotherapy was not. Conclusions. The mechanisms of peripheral retinal ablation controlling ocular growth may through both of retinal and scleral effects.