Clinical Relevance of Feline Hypertensive Oculopathy & Iris Vasculature Involvement

Systemic hypertension is commonly accompanied by secondary ocular changes (ie, feline hypertensive oculopathy), often leading to referral to a veterinary ophthalmologist for further management due to the risk for blindness in these patients. Ocular signs of systemic hypertension typically involve the posterior segment of the eye (eg, retinal detachment, retinal edema and hemorrhage, retinal degeneration); however, the anterior segment can also be involved. This primarily manifests as hyphema or changes in the iris vasculature.¹

In this retrospective study, medical records of 206 cats with documented hypertension (systolic blood pressure, >170 mm Hg), fundic changes typical of hypertension in at least one eye, and at least one follow-up visit with documented response to amlodipine were reviewed with the purpose of describing the prevalence and cause of iris aneurysm in cats with hypertensive oculopathy. Of the 206 cats, 14% had vascular changes of the iris that were consistent with iris aneurysm. Hyphema was present in 30% of all cats; of those with iris vasculature changes, 75% had hyphema. A strong correlation was found between iris aneurysm and hyphema, suggesting that leaky iridal vessels secondary to hypertension may be a common cause of hyphema in these patients. Previous studies have proposed hyphema in hypertensive cats to be caused by massive posterior segment hemorrhage migrating through the pupil.¹

Fundic changes and hyphema were negatively correlated in this study. Of the cats with grade I (ie, retinal folds) or grade II (ie, focal retinal edema/bullous elevation) fundic changes secondary to systemic hypertension, 57.1% and 59.4%, respectively, had hyphema. However, cats with grade III (ie, segmental retinal detachment/hemorrhage) and grade IV (ie, full retinal detachment/hemorrhage) fundic changes had a lower percentage of hyphema (23.9% and 18.8%, respectively). This indicates that hyphema in cats with systemic hypertension is more commonly seen when less severe, nonhemorrhagic fundic changes are present.

Histopathologic examination was performed on one eye in this study and confirmed the presence of iris aneurysm, which was noted to likely be the cause of hyphema for that patient, thus providing further evidence that hyphema secondary to systemic hypertension in cats may be associated with iris vasculature changes.

Key pearls to put into practice:

Early referral to a veterinary ophthalmologist for management of the ocular signs secondary to feline systemic hypertension is important for the success of these patients.

Blood pressure should be measured in all patients presented with hyphema.

This study’s findings cannot be generalized to canine patients; iridal vascular changes seen in cats with systemic hypertension may be secondary to species-specific characteristics of the iris vessels.