Review Question - QID 218488

This patient with a history of obesity, hypertension, hypercholesterolemia, diabetes, and tobacco use who presents with unilateral, painless, acute-onset vision loss, retinal whitening, and a cherry-red spot in the macula most likely has central retinal artery occlusion (CRAO).

CRAO refers to the compromise of blood flow through the central retinal artery leading to retinal infarction.

Etiologies of CRAO include atheroemboli from the carotid arteries and central retinal artery thrombosis. Causes of central retinal artery thrombosis include trauma, sickle cell disease, hypercoagulability, giant cell arteritis, and collagen vascular disease. Risk factors for CRAO include obesity, hypertension, tobacco use, hypercholesterolemia, diabetes, atrial fibrillation, and ipsilateral internal carotid artery stenosis. CRAO usually presents as unilateral, painless, acute vision loss occurring over seconds. Fundoscopic examination usually shows retinal whitening (caused by retinal edema), a cherry red spot (preserved choroidal circulation surrounded by edematous retina), boxcarring of retinal arterioles (indicative of slow flow), and a normal optic disk. CRAO should be treated as an acute stroke, and immediate evaluation with an emergent ophthalmic exam, neurologic exam, and laboratory studies (erythrocyte sedimentation rate, C-reactive protein, platelet count, and coagulation studies) should be performed. Administration of intravenous tissue plasminogen activator (tPA) is a potential treatment option for CRAO, although the evidence is mixed. Although often used empirically, there is less robust evidence for other treatments such as ocular massage, anterior chamber paracentesis, and intraocular pressure reduction with acetazolamide and/or beta-blockers.

Mac Grory et al review the epidemiology, pathophysiology, diagnosis, natural history, and treatment of patients with CRAO. The authors note that a narrow time window exists for the effective treatment of CRAO. The authors recommend that patients with suspected CRAO be rapidly triaged with ophthalmic, neurologic, and laboratory assessments.

Figure/Illustration A shows a photograph of the fundus of the left eye. Diffuse whitening of the posterior pole of the retina (blue arrow) and a cherry-red spot in the center of the macula (yellow circle) are both typical findings in CRAO.

Incorrect Answers:
Answer 2: Central retinal vein occlusion is a cause of unilateral vision loss. However, diffuse retinal hemorrhages and dilated, tortuous retinal veins (blood and thunder appearance) would be expected on fundus examination.

Answer 3: Commotio retinae can cause decreased vision in the setting of recent trauma. It can present with retinal whitening due to intracellular edema of the retinal pigmented epithelium and photoreceptor outer segments. Occasionally, this condition can also mimic a cherry-red spot in the posterior pole. However, in this patient without a history of recent trauma, CRAO is more likely than commotio retinae.

Answer 4: Posterior cerebral artery stroke can cause painless, acute onset, unilateral vision loss. However, unlike in CRAO, patients would be expected to have normal fundus examinations and complete vision loss on the affected side.

Answer 5: Tay-Sachs disease is a rare neurodegenerative lysosomal storage disorder caused by a mutation in hexosaminidase A (HEXA). The disease usually presents around the age of 6 months with abnormal startle responses and hypertonia. A cherry-red spot may also be seen in the macula. There is a late-onset form of this disorder that presents around 30 to 40 years of age with ataxia, dysarthria, spasticity, cognitive decline, and psychiatric illness. However, Tay-Sachs disease is not a cause of sudden-onset vision loss.

Bullet Summary:
Central retinal artery occlusion (CRAO) presents with unilateral, painless, acute vision loss, retinal whitening, and a cherry-red spot in the macula.