Ischemic hypertension of pigeon eye

Purpose: To determine the etiology of open-angle glaucoma in human eyes, we tested the hypothesis that ischemia of the endothelial cells lining Schlem m's canal alters the intraocular pressure (IOP) by affecting the transport of fluids out of the eye. Methods: Experiments were conducted on pigeons. After blacking the tno majo r arteries to the aqueous sinus artery of one eye by laser photocoagulation . the episcleral arteries of both eves were cauterized. The IOP was measure d with a Mentor pneumatonometer before, immediately and several days after blocking the major arteries. Results: After the episcleral cauterization, the IOP of the laser-treated e ye rose significantly and was maintained for at least 3 hours. By day 2, th e IOP had recovered to the pre cauterization level. The IOP of the control eye remained unchanged throughout the experiment. Conclusion: These results strongly support the hypothesis that ischemia of the endothelial cells lining Schlemm's canal plays a role in the control of the IOP. (C) 2001 Japanese Ophthalmological Society.