Vets commonly perform eye exams because eye-related problems are common in horses. Aside from being a fragile and extremely intricate mechanism unto itself, the eye is also a window into the overall health of any animal and reflects changes in the other body systems, especially the cardiovascular system. Proper function of the eye requires proper brain, nerve and muscle function.

I start by assessing the eyes from a distance, and comparing one to the other for symmetry. I generally assess vision by carefully interpreting the menace response. I look at the eye generally, then use an ophthalmoscope to visualize the deeper parts of the eye. I stain the cornea using fluorescein dye if I suspect there is a break in the corneal surface.

Our ability to thoroughly evaluate the back of the eye (fundic examination) is dependent upon the pupil being dilated. The pupil reflex dilates in low light conditions, so to do this exam, we typically move the horse into the darkest area available. A thorough examination does require short term pharmacologic dilation of the pupil. This requires application of medication to the eye.