A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 62-year-old woman is brought to the emergency department because of sudden loss of vision in her right eye that occurred 50 minutes ago. She does not have eye pain. She had several episodes of loss of vision in the past, but her vision improved following treatment with glucocorticoids. She has coronary artery disease, hypertension, type 2 diabetes mellitus, and multiple sclerosis. She underwent a left carotid endarterectomy 3 years ago. She had a myocardial infarction 5 years ago. Current medications include aspirin, metoprolol, lisinopril, atorvastatin, metformin, glipizide, and weekly intramuscular beta-interferon injections. Her temperature is 36.8°C (98.2°F), pulse is 80/min, and blood pressure is 155/88 mm Hg. Examination shows 20/50 vision in the left eye and no perception of light in the right eye. The direct pupillary reflex is brisk in the left eye and absent in the right eye. The indirect pupillary reflex is brisk in the right eye but absent in the left eye. Intraocular pressure is 18 mm Hg in the right eye and 16 mm Hg in the left eye. A white, 1-mm ring is seen around the circumference of the cornea in both eyes. Fundoscopic examination of the right eye shows a pale, white retina with a bright red area within the macula. The optic disc appears normal. Fundoscopic examination of the left eye shows a few soft and hard exudates in the superior and nasal retinal quadrants. The optic disc and macula appear normal. Which of the following is the most likely diagnosis?
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A
Central serous retinopathyIncorrect. Central serous retinopathy causes a subacute, painless central scotoma with a serous macular detachment — not sudden complete vision loss or a pale retina with cherry-red spot.
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B
Acute angle-closure glaucomaIncorrect. Acute angle-closure glaucoma presents with severe eye pain, a hard red eye, corneal edema, and mid-dilated fixed pupil — not painless vision loss with a normal-appearing optic disc.
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C
Vitreous hemorrhageIncorrect. Vitreous hemorrhage obscures the fundus and presents with 'floaters' or a red/black haze — not a pale retina with a cherry-red spot.
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D
Central retinal artery occlusionCorrect. Sudden painless monocular vision loss with pale retina, cherry-red macular spot, and afferent pupillary defect in an atherosclerotic patient is CRAO.
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E
Optic neuritisIncorrect. Optic neuritis (which she has had previously, given her MS history) causes painful, subacute vision loss with a normal or slightly swollen disc — not the sudden painless vision loss with a pale retina and cherry-red macular spot described here.
↑ Tap an answer to reveal the reasoning
Answer: D. Sudden, painless, monocular loss of vision with a pale retina and a 'cherry-red spot' at the macula is the textbook description of central retinal artery occlusion (CRAO). The pale retina results from infarction of the inner retinal layers, and the cherry-red spot is the underlying choroidal circulation showing through the thin, transparent fovea (which has no overlying ganglion cell layer).
This patient has multiple atherosclerotic risk factors (CAD, prior MI, hypertension, diabetes, prior carotid endarterectomy), and the most likely mechanism is embolic occlusion of the central retinal artery from a carotid or cardiac source. The afferent pupillary defect (absent direct, preserved consensual on the affected side; absent indirect, preserved direct on the unaffected side — described here as 'indirect reflex brisk in right but absent in left') confirms an optic nerve/retinal lesion. The white corneal arcus and CV risk profile reinforce the atherosclerotic substrate.
Distractors: central serous retinopathy causes subacute, milder vision loss with a serous macular detachment (not light perception loss). Acute angle-closure glaucoma is acutely painful with a hard, red eye and corneal edema. Vitreous hemorrhage obscures the retina ('floaters' or red haze) rather than producing a pale retina with a cherry-red spot. CRAO is a stroke equivalent and warrants urgent stroke workup.
**Why each option:**
**A.** Central serous retinopathy causes a subacute, painless central scotoma with a serous macular detachment — not sudden complete vision loss or a pale retina with cherry-red spot.
**B.** Acute angle-closure glaucoma presents with severe eye pain, a hard red eye, corneal edema, and mid-dilated fixed pupil — not painless vision loss with a normal-appearing optic disc.
**C.** Vitreous hemorrhage obscures the fundus and presents with 'floaters' or a red/black haze — not a pale retina with a cherry-red spot.
**D.** Correct. Sudden painless monocular vision loss with pale retina, cherry-red macular spot, and afferent pupillary defect in an atherosclerotic patient is CRAO.