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Effect of single‐ and multiple‐dose 0.5% timolol maleate on intraocular pressure and pupil size in female horses
Author(s) -
Woerdt Alexandra,
Wilkie David A.,
Gilger Brian C.,
Strauch Stephen M.,
Orczeck Shawn M.
Publication year - 2000
Publication title -
veterinary ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.594
H-Index - 50
eISSN - 1463-5224
pISSN - 1463-5216
DOI - 10.1046/j.1463-5224.2000.3230165.x
Subject(s) - timolol , intraocular pressure , pupil , pupil size , medicine , ophthalmology , anesthesia , pupil diameter , biology , neuroscience
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.