Laser Treatments Increase Equine Ophthalmology Offerings

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Credit: Courtesy UC Davis A cyst is clearly visible in the lower portion of this horse's eye.

Credit: Courtesy UC Davis A cyst is clearly visible in the lower portion of this horse's eye.

The UC Davis Veterinary Medical Teaching Hospital recently acquired equipment that has increased its service offerings for equine ophthalmology patients. The semiconductor diode laser device allows ophthalmologists to perform new treatments on horses’ eyes, including cyst removal and glaucoma treatment. These procedures have been successful for human and animal patients, and now are available at UC Davis for use in horses the first time.

Horses can develop cysts from their iris for no known reason. If left untreated, these cysts can grow and may cause irritation to the horse or become visually obstructive. Horses are also known to become “spooked” by seeing the cyst in their field of vision. Removal of cysts is now a one-time, outpatient procedure. The laser simply “zaps” the cyst multiple times until it creates a hole causing the cyst to rupture and deflate, without damaging other vital structures in the eye. After care is generally a short course of topical anti-inflammatory ointment for no more than a week.

More importantly for horses, the laser can also be used to treat glaucoma, an increase in pressure inside of the eye. This increased pressure, if left untreated, eventually destroys the retina and optic nerve, and ultimately causes blindness. Glaucoma occurs due to an inability of fluid (aqueous humor) to drain from inside the eye, most commonly secondary to chronic intraocular inflammation known as equine recurrent uveitis (ERU) or “moon blindness.” ERU is a disease that is very prevalent in horses.

The laser treatment for glaucoma is known as transscleral cyclophotocoagulation (TSCP), and destroys part of the ciliary body which produces the aqueous humor that contributes to the increased pressure. TSCP treatment destroys just enough of the ciliary body to lower the production of aqueous fluid to a point that reduces the intraocular pressure, but not enough to completely stop the production, which the eye needs to remain healthy.

The William R. Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis—a unit of the School of Veterinary Medicine—provides state-of-the-art clinical care while serving as the primary clinical teaching experience for DVM students and post graduate veterinarian residents. The VMTH treats more than 47,000 animals a year, ranging from cats and dogs to horses, cows and exotic species. To learn more about the VMTH, please go to www.vetmed.ucdavis.edu/vmth. Timely news updates can be received on its Facebook (www.facebook.com/ucdavisvetmed) and Twitter (www.twitter.com/ucdavisvetmed) pages.