Effect of hyaluronic acid on intraocular pressure in rats.

PURPOSE To study the effect of acute or chronic intracameral injection of hyaluronic acid on intraocular pressure (IOP) in rats. METHODS Acute or chronic injections of hyaluronic acid were performed unilaterally in the rat eye's anterior chamber, whereas the contralateral eye was injected with saline solution. IOP was assessed daily or weekly by a tonometer in conscious rats. IOP was also assessed in both experimental groups at several intervals during the light-dark cycle. RESULTS A single injection of hyaluronic acid induced an increase of IOP that lasted for 8 days (P < 0.01), whereas its chronic administration during 9 weeks induced a significant and sustained increase in IOP, compared with the eye injected with vehicle (P < 0.01). This hyaluronic acid-induced hypertension was significantly decreased by the application of 1 drop of brimonidine (0.2%), latanoprost (0.005%), or timolol (0.5%). Significant daily variations of IOP were observed in both control and hyaluronic acid-injected eyes, peaking during the dark phase (P < 0.001, ANOVA). CONCLUSIONS These results suggest that the intracameral administration of hyaluronic acid could be a model of ocular hypertension in rats.