DECREASED INTRAOCULAR-PRESSURE INDUCED BY NITRIC-OXIDE DONORS IS CORRELATED TO NITRITE PRODUCTION IN THE RABBIT EYE

Purpose. To evaluate the effect of intraocular administration of nitri c oxide (NO) donors in the rabbit eye on intraocular pressure (IOP), i nflammation, and toxicity. Methods, Intravitreal and intracameral inje ctions of two NO donors, SIN-1 and SNAP, and SIN-1C and BSS were perfo rmed. Clinical examination, IOP measurements, protein evaluation in aq ueous humor, and histologic analysis of the ocular globes were realize d. Nitric oxide release was demonstrated by nitrite production in the aqueous humor and in the vitreous using the Griess reaction. Results. The drastic decrease of IOP, observed after a single NO donor injectio n,was correlated directly with nitrite production and, thus, to NO rel ease. Injection of inactive metabolite of SIN-I, SIN-IC, which is not able to release NO, did not modulate IOP. When administered in the aqu eous humor or in the vitreous, NO did not diffuse from one segment of the eye to another. No inflammation or histologic damage was observed as a result of a single NO donor administration. Conclusions. Nitric o xide is implicated directly in the regulation of IOP and its acute, an d massive release into the rabbit eye did not induce inflammation or o ther growth toxic effects on the ocular tissues.