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Equine Ophthalmology: Cyclosporine Implants

Studies performed at NC State have shown that reservoir devices placed into the eye can allow long-term (more than 4 years) release of low levels of cyclosporine. Studies have also shown that the implants are safe and effective in decreasing inflammation in the equine eye.

Cyclosporine is an immunosuppressant drug that is commonly used for treatment to prevent organ transplant rejection and for treatment of dry eyes in dogs. Cyclosporine is the ideal drug to prevent the recurrence of immune-mediated ocular inflammation like keratitis (IMMK). It suppresses the activity of the T-lymphocyte, which is the most common infiltrating cell in equine recurring uveitis (ERU) eyes.

However, cyclosporine eyedrops or ointment do not penetrate past the cornea and cannot get into the eye to treat the uveitis and oral cyclosporine would likely be too toxic and expensive to give a horse.

Clinical studies in horses with ERU have shown excellent control of the disease. However, this is an experimental device and not approved for use in horses by the FDA.

Is my horse a candidate for cyclosporine implants?

The best candidates for the implant are those with the following characteristics:

  • ERU is controllable with traditional medication, but the horse has frequent recurrences
  • The horse has good vision between episodes
  • The horse has minimal scarring in the eye and no cataract formation
  • There is no retinal degeneration and has good retinal function
  • The horse does not have other systemic illnesses (such as a high titer to leptospirosis)

Your veterinarian’s examination will help determine if your horse is a good candidate.

Who can do the surgery?

There are veterinary ophthalmologists in nearly all areas of the US who are or will be trained to perform the implant surgery.

Please call us at 919-513-6659 to determine the closest ophthalmologist in your area.

What are the success rates?

This is an experimental procedure, however, long-term results have shown that greater than 80% of horses have ERU controlled. Some horses have lost vision after implantation.