Top 5 Ocular Consequences of Systemic Hypertension

Michael H. Brown, DVM, MS, DACVO, Veterinary Ophthalmology Services, Oradell Animal Hospital, Paramus, New Jersey

ArticleLast Updated June 20225 min readPeer Reviewed
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Hypertension is a common cause of vision changes and loss and increased risk for damage to the brain, kidneys, and heart.1-4 Ocular lesions are often an initial clinical sign (see Diagnosing & Treating Hypertension).

Following are the 5 most common ophthalmic sequelae of systemic hypertension in the author’s experience.

1. Decreased Vision/Blindness

Decreased or altered vision, vision disturbance, and sudden blindness are emergencies. Patients with systemic hypertension may exhibit initial clinical signs of acute vision loss with varying degrees of mydriasis (Figures 1 and 2), negative or incomplete pupillary light reflexes, negative to varying degrees of light perception, and/or reduced ability to navigate a maze test or recognize humans.5 Systemic hypertension can cause visual disturbance or acute blindness from intraocular hemorrhage, subretinal edema, retinal detachment, or secondary glaucoma.1,6,7

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Fixed, dilated pupil (common secondary to systemic hypertension) and subsequent serous retinal detachment in a cat

Differential diagnoses for changes in vision are old age, corneal disease, uveitis, cataracts, glaucoma, progressive retinal atrophy (dogs; less common in cats), retinal detachment, retinal edema, sudden acquired retinal degeneration (dogs), and optic nerve or intracranial disease.5 Common causes of vision loss in cats are uveitis, corneal disease, cataracts, glaucoma, retinal degeneration, retinal detachment, retinal edema, and optic nerve and intracranial disease.

2. Retinal Hemorrhage

Retinal hemorrhage is a common sequela to hypertension.1 Hemorrhages may be focal, multifocal, or large hemorrhagic subretinal areas (Figures 3 and 4). The mechanism is related to arteriolar vascular permeability changes.8,9 Autoregulatory mechanisms cause initial vasoconstriction, followed by possible arteriole lumen occlusion and ischemic necrosis. Increased vascular permeability can affect the choroid and cause subretinal fluid and retinal detachment.8,9

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Fresh, characteristic keel-boat–shaped preretinal hemorrhages (arrows) between the retina and vitreous humor secondary to systemic hypertension in a dog

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Multifocal retinal hemorrhages of varying shapes in the tapetum secondary to systemic hypertension in a dog

Retinal hemorrhages are also common with other conditions (eg, trauma, infectious disease, coagulopathy, neoplasia, diabetes, congenital disorders) that cause vasculitis, as well as hyperviscosity syndrome.8 In dogs, tick-borne diseases are infectious agents that can be associated with retinal hemorrhage.8

Differential diagnoses for retinal hemorrhage are coagulopathy, infectious disease, neoplasia, trauma, congenital disorders, and hyperviscosity syndrome secondary to multiple myeloma.

3. Hyphema/Intraocular Hemorrhage

Hyphema is a classification of intraocular hemorrhage that refers to a collection of erythrocytes in the anterior chamber (Figures 5 and 6). Intraocular hemorrhage can develop with any systemic condition that affects the vasculature of intraocular structures and can occur in the anterior chamber, surface of the iris, vitreous cavity, retina, choroid, supra- or subchoroidal space, and around or on the optic disc. Blood accumulates in the anterior chamber or vitreous humor due to disruption of the iris or ciliary body vessels in response to sustained systemic hypertension. Altered permeability of the uveal vasculature (iris, ciliary body, choroid) may then lead to intraocular hemorrhage,8,9 which may be visualized as a few strands of blood in the anterior chamber or on the iris surface, partial or complete hyphema in the anterior chamber, focal or large areas of vitreal hemorrhage, or retinal hemorrhage. Hemorrhage may be substantial and obscure large areas of the fundus, depending on chronicity and severity of systemic hypertension.

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Ventral anterior chamber hyphema secondary to hypertension in a dog

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Progressing hyphema secondary to hypertension in a dog that obscures intraocular structures

Differential diagnoses for intraocular hemorrhage are trauma, intraocular tumor, systemic neoplasia, coagulopathy, chronic glaucoma, chronic uveitis, and retinal detachment.10

4. Retinal Detachment

Exudative or serous retinal detachment is common in patients with hypertension.11 Clear to yellow fluid accumulation or blood in the subretinal space that may appear as the retina billowing toward the examiner is characteristic during ophthalmoscopy (Figures 7 and 8). Retinal detachment can also be secondary to vascular, inflammatory, and/or neoplastic diseases of the retina, choroid, and retinal pigmented epithelium.12

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Serous retinal detachment in a cat with hypertension. Characteristic billowing retina (arrow) due to subretinal fluid is visible.

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Characteristic subretinal edema and billowing of the retina (arrows) associated with systemic hypertension in a cat

Leaking fluid can overwhelm the retinal pigmented epithelium pumping mechanism, causing fluid accumulation in the subretinal space and leading to retinal detachment and vision loss. Vision loss may be acute or gradual and partial or complete, depending on the degree of vitreal hemorrhage and retinal edema. Correction of the underlying cause may allow resorption of subretinal fluid; vision recovery is possible if the condition is treated before retinal ischemia occurs. Morphology of the retina and retinal pigmented epithelium interface may not recover, even after 6 months.13

Less likely differential diagnoses for retinal detachment are systemic infections (eg, fungal, bacterial [eg, ehrlichiosis, borreliosis], protozoal [eg, toxoplasmosis], viral [eg, FeLV, FIP, FIV]), neoplasia (eg, multiple myeloma, lymphoma), primary ocular conditions (eg, glaucoma), and immune-mediated conditions (eg, uveodermatologic syndrome, hyperviscosity syndrome secondary to multiple myeloma).

5. Intraretinal Edema/Vessel Tortuosity

Variations of retinal edema, retinal vessel tortuosity, perivascular edema, and papilledema are possible in patients with hypertension.14 Vascular ischemic changes and changes to vascular permeability occur with hypertension. 

Vascular tortuosity refers to abnormal twists and turns (often at acute angles; different from the natural arborizing branching pattern of retinal vasculature) related to mechanical forces associated with hypertension that affect wall rigidity, blood pressure, blood flow, axial tension, and wall structural changes (Figure 9).15 Retinal edema may appear via indirect ophthalmoscopy as areas of the tapetum that are gray, are indistinct, have altered reflectivity, or have pale yellow or patchy irregularities compared with the surrounding tapetum (Figure 10).

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Tortuous course of retinal vasculature due to hypertension in a dog

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Retinal folding, hemorrhages, and multifocal areas of blurred and indistinct areas in the tapetum of a cat with hypertension

Differential diagnoses for intraretinal edema and vessel tortuosity are fungal, bacterial, parasitic, and protozoal infections; immune-mediated and tick-borne diseases; toxicosis; trauma; algae; metabolic conditions; and neoplasia.


Systemic diagnostic evaluation should be performed to rule out renal disease, endocrine disorders, and cardiac disease. Hypertension may be undetected, as ocular lesions may not occur until blood pressure has been elevated for weeks or months. Blood pressure can increase with age,16 and patients at risk for hypertension (eg, cats >10 years of age, dogs with pre-existing risk factors) may benefit from routine indirect blood pressure measurement and funduscopic evaluation.