Clinical Features and Surgical Outcomes of Cats With Presumed Primary Lens Instability: A Retrospective Study of 34 Cases (2018–2022)

Objective: Describe the clinical features, disease progression, and outcomes of presumed primary lens instability (PLI) in cats, and to assess its association with glaucoma. Animals Studied: Thirty-four cats (68 eyes). Procedures: Medical records were reviewed for signalment, clinical history, ophthalmic findings, and treatment. Eyes were classified as anterior lens luxation (ALL) or subluxated lens (SLL). Clinical monitoring included intraocular pressure (IOP), menace response, absence/presence of blepharospasm, and complications. Surgical eyes underwent intracapsular lens extraction or phacoemulsification, with or without vitrectomy. Results: Cats were 1–13 years old (median 3 years) and predominantly male (82%). At presentation, 68% of eyes had ALL and 32% of eyes had SLL. Blepharospasm was observed in 25% of eyes, mostly in ALL. IOP was elevated (> 25 mmHg) in 38% of eyes overall, comprised of 62% SLL eyes (33 ± 5.7 mmHg) and 25% ALL eyes (54.8 ± 24.1 mmHg). Of SLL eyes followed ≥ 90 days, 73% progressed to ALL within a median of 15 days (5–174 days). Forty-four eyes underwent surgery and, of 42 with follow-up (median 284 days), 95% achieved comfort and 85% retained vision; however, 70% developed postoperative glaucoma within 68 ± 51 days that was still present in 35% of eyes at last recheck. Retinal complications occurred in 14% of operated eyes. Nonsurgical eyes also showed a high risk for IOP elevation. Conclusions: Presumed PLI presents bilaterally in generally young cats, often with limited signs of ocular discomfort, but with a high risk of concurrent or delayed glaucoma. Lens extraction restores comfort and can preserve vision but does not prevent future IOP elevation.