Eye Protection from the Sun

Q. I have a 14-year-old Paint/Quarter Horse with one blue eye that has been diagnosed with a "detached iris." His iris appears wide open or not even there. My vet suggested providing his eyes with protection from the sun. What is available? I would also appreciate any information about the problem itself.

A. A "detached iris" is actually an ophthalmic disease. However, the veterinarian might be referring to several diseases of the iris. This horse might have focal iris hypoplasia, which is a focal area of iris thinning that is common in lightly colored eyes. If the area has been present since birth, it could be a notch defect called an iris coloboma (a problem in which some of the structures of the eye are absent due to incomplete fusion of the fetal intraocular fissure during gestation) or a condition called iris aplasia (lack of development of an organ or tissue). Less commonly, a severe traumatic episode could have caused an iris base disinsertion (which is when the attachments of the iris have been severed or "dislocated" from their attachments to the wall of the eyeball, resulting in bleeding into the chamber of the eye), but this almost always is associated with severe pain and bleeding in the eyes.

Whatever the cause, the veterinarian's advice was sound. Since more light is entering the eye, it might be sensitive. I would recommend a fly mask with the highest amount of UV protection claimed by the manufacturer.

About the Author

Brian C. Gilger, DVM, MS, Dipl. ACVO

Brian C. Gilger, DVM, MS, Dipl. ACVO is an Associate Professor of Ophthalmology at North Carolina State University.

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