Effects of topical application of a 2% solution of dorzolamide on intraocular pressure and aqueous humor flow rate in clinically normal dogs
Cawrse, M.A.; Ward, D.A.; Hendrix, D.V.
American Journal of Veterinary Research 62(6): 859-863
ISSN/ISBN: 0002-9645 PMID: 11400841 DOI: 10.2460/ajvr.2001.62.859
The effects of topical application of a 2% solution of dorzolamide on intraocular pressure (IOP) and aqueous humour flow rate in clinically normal dogs were evaluated. 15 Beagles were utilized in the study. The IOP was measured in both eyes of all dogs for 3 days to determine baseline values. In a single-dose study, 50 micro l of dorzolamide or control solution was applied in both eyes at 7:00 AM, and IOP was measured 7 times/d. In a multiple-dose study, dorzolamide or control solution was applied to both eyes 3 times/d for 6 days, and IOP was measured 4 times/d during treatment and for 5 days after cessation of treatment. Aqueous humour flow rate was measured for all dogs fluorophotometrically prior to treatment and during the multiple-dose study. In the single-dose study, dorzolamide significantly decreased IOP from 30 minutes to 6 hours after treatment. Mean decrease in IOP during this time span was 3.1 mm Hg (18.2%). Maximal decrease was detected 6 hours after treatment (3.8 mm Hg, 22.5%). In the multiple-dose study, dorzolamide decreased IOP at all time points, and maximal decrease was detected 3 hours after treatment (4.1 mm Hg, 24.3%). Mean aqueous humor flow rate decreased from 5.9 to 3.4 micro l/min (43%) after treatment in the dorzolamide group. Topical application of a 2% solution of dorzolamide significantly decreases IOP and aqueous humour flow rate in clinically normal dogs. Therefore, topical administration of dorzolamide should be considered for the medical management of dogs with glaucoma.