A  If you are seriously interested in this horse, you should invest in an examination by a veterinary ophthalmologist. The specifics of the cataracts will affect the prognosis. The term "cataract" only means that there is an opacity to the lens of the eye; that opacity might be a very small spot on the lens or encompass the entire lens. The lens of the eye is normally clear and acts like a camera lens focusing the beam of light entering the eye on the retina in the back for transmission to the brain via the optic nerve. The lens is like a Zip-Lock bag filled with clear Jello; there is a firm capsule on the front and back surface and soft, clear tissue in the middle. Cataracts develop when some process occurs that causes any part of the clear capsule and/or center to become opaque and therefore affect the beam of light entering the back of the eye.

Diffuse cataracts affecting the entire lens occur in foals and are considered a form of congenital eye problems. (Has this horse had them since birth?) The most common cause of cataract formation in the adult horse is inflammation caused by the advanced stages of anterior uveitis or moonblindness (see The Horse, "Periodic Ophthalmia," July 1998, and "Common Problems," April 2000). There are other causes in the adult horse, but they usually only affect one eye