Laser treatment for eye cysts in horses

Iris cysts (often called corpora nigra cysts) form on the colored portion of the eye. (Adobe Stock)

Research from the Netherlands suggests that diode lasers can safely treat iris cysts in horses. A diode laser is a semiconductor device that emits beams that can cut soft tissue.

Iris cysts (often called corpora nigra cysts) form on the colored portion of the eye, appearing as rounded structures along the margin of the pupil. Painless and slow growing, the cysts are generally not a problem. If they become large enough, however, they can interfere with a horse’s vision, causing “spooky” behavior and headshaking.

Retrospective review of cases

Researchers at Utrecht University Equine Clinic reviewed case records of 35 horses treated for iris cysts with a diode laser between 2008 and 2020. Within that group, a total of 46 eyes received treated. The data showed a significant decrease in cyst size in 35 eyes the day after treatment. The presence of multiple or thick-walled cysts reduced the effectiveness of the treatment. Eight horses developed minor complications.

Positive treatment outcomes

Long-term follow up showed the equine eye cysts diminished or disappeared in 93 percent of cases, and 83 percent of the owners said they would recommend the treatment.

Reference: “Noninvasive diode laser, an effective and safe treatment of iris cysts in 46 eyes of 35 horses,Equine Veterinary Journal, May 2022

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