Effect of topical 1% tropicamide on Schirmer tear test results in clinically normal horses

Objective  To observe the effect of topical 1% tropicamide on equine tear production as measured by Schirmer I tear test.
Materials and methods  Fourteen adult horses received one drop of 1% tropicamide ophthalmic solution in one eye and the opposite eye served as the control. The tear production in both eyes was tested at 1, 2, 4, 6, and 24 h after 1% tropicamide administration.
Results  Measurements made 1 h after treatment revealed a significant reduction in Schirmer tear test values in tropicamide treated eyes ( P  = 0.002). The observed decrease in tear production was maintained up to 4 h after treatment ( P  = 0.002). Although tropicamide-induced decrease in STT values was observed in the treated eyes, the contralateral eyes did not show significant changes in Schirmer tear test results.
Conclusion  Single dose of topical 1% tropicamide resulted in statistically significant reduction in Schirmer tear test values in clinically normal horses.