Limbal cystotomy by fine needle aspiration of a translucent iris cyst in a horse

Summary A 4‐year‐old Cremello crossbred mare was referred to the Equine Veterinary Teaching Hospital of Utrecht University for a translucent iris cyst from the dorsal pupillary margin corpora nigra in the right eye. Although noninvasive diode laser treatment is the preferred method of pigmented cyst ablation, two attempts did not result in disruption of the translucent iris cyst in this case, probably due to the minimal amount of pigment in the cyst. After those unsuccessful attempts, the horse was put under general anaesthesia and a limbal cystotomy by fine needle aspiration of the cyst was performed successfully. During the procedure, a small amount of cyst wall material was accidentally pulled into the limbus at the site of the fine needle aspiration, causing hyperaemia that resolved within 40 days. No recurrence of the iris cyst was reported up to 15 months after treatment. To the author's knowledge, this case report is the first to describe a successful treatment method for translucent iris cysts in horses.