Neuroprotective Effect of Topical Administration of Alphagan-P in Rats With Laser-Induced Chronic Ocular Hypertension

Abstract

Abstract: : Purpose: Evaluation of topical administration of brimonidine, purite formulation (Alphagan-P) on retinal ganglion cell (RGC) survival in ocular hypertensive rats. Methods: Intraocular pressure (IOP) was elevated by laser photocoagulation of limbal and episcleral veins. Two laser treatments were done with one-week interval. Drug administration was begun on day 10-post laser treatment and continued for 21 days. Drug was applied twice a day at 5 µl. in the laser treated eyes only. IOP was monitored weekly before and one hour after drug administration. At the end of the experiment RGC's were labelled by retrograde transport, and counted in whole mounted retinas. Result: Laser treatment caused a two-fold increase in IOP. One hour after topical application, Alphagan–P caused decrease in IOP by 33% (day 1 of treatment) and by 25% (day 15 of treatment). There was a 17% decrease in RGC 10 days after IOP elevation. In vehicle treated group there was a 41% decrease in RGC after 21-day treatment. However in Alphagan–P treated groups there was a 16% decrease, that is no additional decrease from the 10-day cell loss. Conclusions: Topical application of Alphagan-P was effective in protecting ganglion cells in (chronically ocular hypertensive) COHT rats, This indicates that Alphagan–P applied topically reaches the retina to cause its neuroprotective activity on RGC's.

Keywords: drug toxicity/drug effects • neuroprotection • intraocular pressure