Glaucoma in horses
Glaucoma is a rather rare but serious eye condition in the horse. Glaucoma can lead to pain, blindness and even removal of the eye if left untreated. Contact your veterinarian if you suspect your horse has glaucoma.
What is glaucoma?
Glaucoma is a severe eye problem that occurs in less than 1 in 1,000 horses. It stems from poor fluid drainage that increases pressure in the eye. Usually this fluid drains from the eye at the same rate it’s produced.
If left untreated, glaucoma can result in pain and blindness. At the end stages, veterinarians often recommend removing the eye to relieve the pain.
What horses are prone to glaucoma?
Glaucoma usually occurs in horses that also have moon blindness. Swelling from moon blindness can block fluid drainage in the eye.
Signs of glaucoma
Cloudy blue cornea sometimes with white lines crossing it
Redness in the white tissues around the cornea
Signs of pain such as squinting and tearing
Big pupils that don't shrink in bright light
An enlarged eye
Veterinarians diagnose glaucoma by completing an eye exam. They will often use local anesthetic blocks to help with the exam. The horse may need sedation depending on its temperament. The veterinarian will measure the pressure on the eye to diagnose glaucoma.
The goal of treatment is to lower the pressure in the eye. You should first try topical treatments such as eye drops or eye ointments. Be careful as some horses may not tolerate these.
Dorzolamine hydrochloride is a topical medication given three times daily. It reduces the amount of fluid produced in the eye.
Timolol is a topical medication given every 12 hours. It can mildly lower the pressure by reducing the amount of fluid produced. It’s often given with dorzolamine.
Systemic non-steroidal anti-inflammatories (such as banamine) and topical corticosteroid ointment can reduce swelling if moon blindness is present.
If topical therapy doesn’t control the glaucoma or isn’t an option, surgery may be an option.
In this procedure, veterinarians use a laser to destroy some parts of the eye that produce fluid. Horses can undergo this procedure with general anesthesia or standing sedation with local anesthesia. The procedure can accomplish the following:
Reduce the pressure in the eye
Decrease or eliminate the need for topical medication
Maintain comfort and vision
Gonioimplantation is placing a tiny drain in the eye to increase fluid drainage. This procedure has a low success rate and is less common.
Reviewed in 2018