Diode laser ablation of progressive pigmented iris lesions in 317 cats (356 eyes) appears overall safe and effective in decreasing progression of iris pigmentation.

Objective: To describe a novel scoring system of feline pigmented iris lesions prior to utilization of diode laser ablation of progressive pigmented iris lesions and to retrospectively evaluate short- and long-term patient outcomes following transcorneal diode laser ablation.
Animals: 317 client-owned cats (356 eyes) were included.
Clinical Presentation: Records of cats undergoing diode laser ablation from January 2000 to December 2018 were retrospectively reviewed. A novel clinical grading system to describe severity of feline iris hyperpigmentation was developed. Recorded parameters included signalment, operated-upon eye, presurgical iris pigmentation score, intraocular pressure, visual status, postoperative complications, repeat laser surgery, patient status at last follow-up, time to death, and presumptive or known cause of death.
Results: Complications included corneal ulceration (25/356 [7%]), glaucoma (18/356 [5%]), uveitis (4/356 [1.1%]), and corneal edema (3/356 [0.8%]). Enucleation was performed in 12 eyes due to blindness and secondary glaucoma. Repeat laser due to continued progression of pigment was performed in 18.5% of eyes. Two study patients were euthanized due to presumptive metastatic disease. Of the 250 cats for whom confirmation was available via phone call or medical records, 240 (96%) were alive at 1 year.
Clinical Relevance: Diode laser ablation appears safe overall and may be effective in decreasing progression of feline iris pigmentation. Complication risks appear minimal.