Study: Diode Lasers Can Alleviate Iris Cysts In Horses

The structure of the equine eye is unique for many reasons, one of which is the presence of the corpora nigra. The corpora nigra diminishes glare from light, similar to how a shade cloth operates.

Horses can develop cysts on their irises, the colored part of their eye. Called corpora nigra cysts, these appear as round structures around the margin of the pupil. Though they're painless and slow-growing, if the cysts become big enough they can interfere with a horse's ability to see, which can cause issues like spooking and head shaking.

Researchers from the Utrecht University Equine Clinic in the Netherlands used a diode laser to treat cysts in horses that were referred to their clinic. A diode laser emits a beam that can cut soft tissue. The scientists looked at 35 horses that had been treated with a diode laser in the clinic between 2008 and 2020.

In total, 46 eyes were treated with laser therapy. The data showed a significant decrease in cyst size in 35 of the eyes the day after the treatment was administered. It was noted that if multiple or thick-walled cysts were present, the effectiveness of the treatment was reduced. Eight study horses developed minor complications.

Long-term, eye cysts diminished or disappeared in 93 percent of the cases; 83 percent of the owners would recommend the treatment.