EXPERIMENTAL GLAUCOMA MODEL IN THE RAT INDUCED BY LASER TRABECULAR PHOTOCOAGULATION AFTER AN INTRACAMERAL INJECTION OF INDIA INK

A simple and reproducible rodent glaucoma model is required to elucida te the pathophysiology of damage to the optic nerve. We developed chro nically elevated intraocular pressure (IOP) unilaterally in rats by in jecting india ink into the anterior chamber of one eye using a 30-gaug e needle. One week later, trapped carbon particles in the chamber angl e formed a black band along the corneal limbus in the injected eyes. W e performed direct laser photocoagulation without a gonio lens, and se lectively burned the trabecular meshwork. Intraocular pressure was mea sured every week and laser photocoagulation was repeated until mean IO P in the experimental eyes rose above 25 mmHg. Unilateral IOP elevatio n was attained in all rats within 4 weeks. Twelve weeks after ink inje ction, we sacrificed the rats and excised the eyes for histologic anal ysis. The anterior chamber angle showed peripheral anterior synechia c aused by laser photocoagulation, and carbon particles were engulfed by macrophages that infiltrated the ciliary cleft. Ln the optic nerve he ad, a remarkable decrease in the nel ve fiber layer and cavernous dege neration were observed, suggesting glaucomatous optic nerve damage. Th is experimental rodent model should facilitate the study of the comple x mechanisms involved in glaucoma. Jpn J Ophthalmol 1998;42:337-344 (C ) 1998 Japanese Ophthalmological Society.