Iris aneurysm in feline hypertensive oculopathy.

To describe and document the prevalence and cause of iris aneurysm in feline hypertensive oculopathy.Privately owned cats with systemic hypertension presented for sudden visual deficits and/or hyphema.A retrospective search of medical records of cats with systemic hypertension was performed in a specialized eye practice from October 2001 to August 2016. Inclusion criteria used for further evaluation were (1) systolic blood pressure exceeding 170 mm Hg measured by Doppler ultrasound, (2) typical fundus changes consistent with systemic hypertension (retinal folds, retinal edema, intraretinal bullous fluid accumulation, retinal detachment-partial or total, intra-/preretinal bleeding) in at least one eye, and (3) at least one follow-up visit with documented response to therapy with amlodipine. Cats with bilateral hyphema were excluded.A total of 206 cats fulfilled the inclusion criteria. Twenty-eight cats (14%) showed an aneurysm of the iridal vessels, 21 75% with some amount of hyphema. In total, hyphema was present in 62 cats (30%). Pearson correlation of fundus changes, hyphema, and aneurysm was performed. A high correlation between fundus changes without posterior segment hemorrhage and hyphema was found. The histopathology of one eye showed iridial vascular changes compatible with an aneurysm. In 75 cats, additional blood analysis was performed. Presumed chronic kidney disease (80%) was the most common cause of systemic hypertension with eye disease, followed by hyperthyroidism (20%).Vascular changes of the iris compatible with aneurysms were seen in 14% of cats with systemic hypertension and may result in vascular rupture and acute hyphema.