- Clinical science
Retinal artery occlusion refers to occlusion of the central retinal artery and/or its branches, usually as a result of thromboembolic phenomena. Common risk factors include atherosclerosis, atrial fibrillation, and vasculitis (e.g., temporal arteritis). Central retinal artery occlusion (CRAO) is characterized by sudden, painless loss of vision and a relative afferent pupillary defect. Ophthalmoscopy reveals a pale, edematous retina and a cherry-red spot in the foveal region. Branch retinal artery occlusion (BRAO) presents with specific patterns of visual field defects depending on which branch is involved. Treatment is usually ineffective because of irreversible ischemic damage to the retina. The prognosis is especially poor if the macula is involved. Retinal vein occlusion is more common than retinal artery occlusion and follows a less fulminant course. Risk factors for central retinal vein occlusion include prothrombotic states and raised intraocular pressure. Retinal vein occlusion may involve the central retinal vein and/or one of its branches. Branched retinal vein occlusion (BRVO), which is more common than central retinal vein occlusion (CRVO), is usually asymptomatic unless the macula is involved. CRVO may be either non-ischemic or ischemic: Non-ischemic CRVO, which is more common than the ischemic variant, presents with minimal retinal hemorrhage on ophthalmoscopy and mild to moderate loss of vision. Ischemic CRVO presents with severe loss of vision, a relative afferent pupillary defect, and extensive retinal hemorrhage on ophthalmoscopy. Fluorescein angiography is required in order to differentiate between ischemic and non-ischemic retinal vein occlusion. The prognosis of ischemic CRVO is less favorable since it is associated with neovascular glaucoma and retinal detachment. While BRVO and non-ischemic CRVO usually do not require any treatment, ischemic CRVO requires laser therapy.
Incidence in the general population:
- CRAO: 5/1,000,000
- BRAO: 3/1,000,000
- Age of onset: > 60 years
- Sex: ♂ > ♀
- Race: no specific racial predisposition
Prevalence in the general population:
- CRVO: 1/1,000
- BRVO: 6/1,000
- Age of onset: > 80 years
- Sex: ♂ = ♀
- Race: slightly higher prevalence among Latinos and Asians
Epidemiological data refers to the US, unless otherwise specified.
- Thrombosis of the retinal vessels (usually as a result of atherosclerosis)
- Rare causes: vasculitis (e.g., temporal arteritis), arterial vasospasm, fibromuscular dysplasia
The exact cause of thromboembolic retinal vein occlusion is unknown, but risk factors include:
- Systemic diseases: , ,
- Hypercoagulable/prothrombotic states (e.g., polycythemia vera, sickle cell disease, oral contraceptive use)
- Ocular diseases:
|Symptoms|| || |
|Relative afferent pupillary defect|| || |
|General physical examination|
|Non-ischemic CRVO||Ischemic CRVO|
|Symptoms|| || || |
|Relative afferent pupillary defect|| || || |
- Definition: sudden, painless loss of vision that lasts for seconds to minutes and is followed by spontaneous recovery (mostly unilateral)
- Cause: retinal ischemia following transient occlusion of the central retinal artery by microemboli
- Although amaurosis fugax is self-limiting, it is a harbinger of more serious conditions. Therefore, perimetry and treatment of the underlying cause are essential:
Retinal vessel occlusion is primarily a clinical diagnosis (based on the patient's history and fundus examination). Additional investigations are usually performed to identify underlying risk factors, to differentiate between subtypes (e.g., in the case of CRVO).
- One or both of the following tests are performed if fundus examination is normal but retinal artery occlusion is still suspected based on the patient's history:
- Fluorescein angiography
- Electroretinography: shows decreased b-wave amplitude
- Evaluation for cardiovascular risk factors:
- Tests to rule out temporal arteritis:
- Fluorescein angiography: in order to differentiate ischemic from non-ischemic forms of retinal vein occlusion
- Electroretinography: Decreased b-wave amplitude is seen in ischemic CRVO.
- Optical coherence tomography may be performed to look for macular edema.
- Eyeball massage
- Carbogen therapy: inhaling a mixture of 5% CO2 and 95% O2
- Decrease intraocular pressure; with drugs and/or surgical therapy (e.g., paracentesis of the anterior chamber)
- Vasodilators (e.g., calcium channel blockers, sublingual nitroglycerine)
- High-dose glucocorticoid therapy if temporal arteritis is suspected
At the onset of symptoms, hemodilution with the help of IV fluids (with the aim of decreasing hematocrit to 35%) might improve retinal blood flow. Further management depends on the type of retinal vein occlusion:
Ischemic CRVO must be treated with:
- Laser therapy
- Panretinal photocoagulation
- If macular edema is present: grid photocoagulation
- Intravitreal injection of VEGF inhibitors and/or steroids
- Laser therapy
- BRVO and non-ischemic CRVO usually do not require treatment.
- Neovascularization of the iris ; () → neovascular glaucoma
- Neovascularization of the retina → vitreous hemorrhage → retinal detachment
We list the most important complications. The selection is not exhaustive.
- Central retinal artery occlusion: severe loss of vision
- Branch retinal artery occlusion: loss of vision and/or visual field defects (depending on which branch of the retinal artery is affected)
- Rule of thirds: Visual acuity improves in one-third of cases, remains the same in another third, and worsens in the remaining third.
- The prognosis is especially poor in the case of ischemic CRVO.