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Editor’s Note: This article was revised by the author to reflect new and updated information in November 2017.

A cataract can partially or fully obscure your horse’s vision, but surgical treatment can be successful

Everyone has heard of cataracts. We think of them as affecting older humans, and sometimes they are found in children and young adults. Yet, cataracts also are seen in horses. A cataract is an opacity or clouding of the lens (a large transparent structure found midway between the cornea and the retina that is used to focus images close to the horse’s head.

The lens has an outer cortex region and an inner nuclear (center) portion. Made of a multitude of individual fibers, the lens is suspended in place by zonules (ligaments holding the lens in position) attached to the ciliary body. When lens fibers grow, they form lens suture lines that can be seen in many foals. The anterior suture has a “Y” shape with the posterior suture varying in shape from a “Y” to a sawhorse or star pattern. The anterior sutures are difficult to visualize in Thoroughbreds, but easier to see in Standardbred and Saddlebred foals