Effect of single- and multiple-dose 0.5% timolol maleate on intraocular pressure and pupil size in female horses.
OBJECTIVE: To determine the effect of single and multiple-dose 0.5% timolol maleate on intraocular pressure (IOP) and pupil size between 8 AM and 8 PM. Animals Nine female horses with normotensive eyes. Procedure IOP, horizontal and vertical pupil size were measured on a single day, between 8 AM and 8 PM at hours 0, 0.5, 1, 2, 4, 6, 8, 10, and 12. A single dose of 0.5% timolol maleate was applied to both eyes immediately after the first measurement at 8 AM. IOP and pupil size were measured at 8 AM and 4 PM in a 5-day experiment of twice-daily application of 0.5% timolol maleate. RESULTS: A significant decrease in IOP from 24.9 +/- 4.2 mmHg prior to application of timolol maleate to 20.7 +/- 3.1 mmHg (4.2 mmHg = 17%) was observed 8 h after single-dose application. A significant decrease in horizontal pupil size (2.0 mm = 11%) was present 6 h after single-dose application. In the multiple-dose experiment, a significant decrease in IOP was present on days 4 and 5 as compared to IOP measured prior to application of timolol maleate. A significant decrease in horizontal and vertical pupil size was present throughout the 5-day study as compared to the values obtained prior to treatment. CONCLUSIONS: 0.5% timolol maleate significantly decreased IOP and pupil size in normo-tensive eyes of this group of female horses in both single and multiple twice daily applications.
Van Der Woerdt
A.
A
Department of Veterinary Clinical Sciences, The Ohio State University, College of Veterinary Medicine, Columbus, OH 43210. Present addresses: The Animal Medical Center, 510 East 62nd Street, New York, NY 10021, USA; Department of Veterinary Clinical Sciences, The Ohio State University, College of Veterinary Medicine, Columbus, OH 43210, USA; Department of Veterinary Clinical Sciences, The Ohio State University, College of Veterinary Medicine, Columbus, OH 43210. Present address: Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
Wilkie
D.A.
DA
Gilger
B.C.
BC
Strauch
S.M.
SM
Orczeck
S.M.
SM