All newborn foals should have an exam by a veterinarian at 12 hours after birth, and this should include an eye exam. Horse’s eyes are very sensitive and the foal’s eyes are even more sensitive, so it is critical to make sure the eyes are normal at birth. Any amount of swelling around the eyes should always be a concern and if the foal is squinting, then we know the eye is painful and needs to be examined. Any discharge from the foal’s eye is also potentially serious as a severe infection could cause the foal to lose the eye in a matter of hours.
Dr. Dennis Brooks indicates in the Horse.com that you can watch the upper eyelid lashes and if the lashes droop or if you see increased blinking of one eye more than the other, the eye is painful. Foals can suffer eye damage at birth but this is mostly hemorrhage from trauma that usually does not cause a permanent problem. Once the foal is on the ground, exposure to all sorts of organisms and environmental irritants occurs and Dr. Steve Roberts indicates corneal ulcers can be a major problem in foals. Dr. Nancy Loving indicates that foals can have many eye conditions at birth, such as cataracts, smaller than normal eyes, and deviation of the eyeball. Also, foals that become sick from diseases unrelated to the eyes are susceptible to eye disease as their immunity is decreased and many sick foals are dehydrated; this causes the globe to sink back into the eye and allows eyelid hairs to rub on the outer surface of the eyeball. So the major point is that if you have a foal and you even think there may be an eye problem, there probably is so have your veterinarian check it out.