The role of inflammation in CW Nd:YAG contact transscleral photocoagulation and cryopexy.

Cyclodestructive modalities in humans have been shown to be effective when applied 3.5 mm or more posterior to the limbus. Therefore, CW Nd:YAG contact transscleral laser and cryopexy were applied 6 mm posterior to the limbus of pigmented rabbits. The intraocular pressure (IOP), flare, iritis, cells and conjunctival hyperemia were monitored clinically up to 3 weeks. The pressure lowering effect was -7.5 +/- 7.7 mm Hg for laser retinopexy and -14.2 +/- 6.0 mm Hg for retinocryopexy at 3 weeks and was comparable to application of the same modalities directly over the ciliary body. Similarly, induction of intraocular inflammation by injecting 10 micrograms of endotoxin intravitreally lowered IOP significantly. These findings suggest that hypotension may not be directly due to cyclodestruction but may be related to the ocular irritative response and extent of neuroepithelial defect, irrespective of its distance from the limbus.