Lens Implants in Horses Advocated Following Cataract Surgery

Horses that have undergone cataract surgery to remove the damaged intraocular (inside the eye) lens now have more appropriate replacement lens options.

After cataract surgery horses are still able to see, but without inserting a replacement lens, they have abnormal vision. These aphakic (no lens) horses are unable to properly focus light on the retina, making images appear larger and less focused.

Brian Gilger, DVM, MS, Dipl. ACVO, a professor in the department of clinical sciences at North Carolina State University’s College of Veterinary Medicine, and colleagues surgically implanted 25-diopter (D) lenses into the four adult horses undergoing cataract surgery. The researchers then used retinoscopy and ocular ultrasonography to assess the lenses.

"We found that the 25-D lenses were too strong and overcorrected the eyes," noted Gilger. "Our data indicate that 18-D intraocular implants are more appropriate; however, more studies are needed to confirm this hypothesis."

He added, "The 18-diopter lens has been used in several horses since this study was done and appears to be the correct lens to use."

Gilger also noted that the use of these lenses has become the "standard of care" in horses following cataract surgery to achieve emmetropia--the condition of having a lens that can properly focus objects on the retina. Such lenses are now commercially available.

The study, "Evaluation of 30- and 25-diopter intraocular lens implants in equine eyes after surgical extraction of the lens," was published in the July 2010 edition of the American Journal of Veterinary Research.

The abstract is available on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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