An 80-year-old man consults you for sudden painless loss of vision in his left eye today. He has complained of headache and pain on chewing for several weeks. His visual acuity in the right eye is normal; in the left eye, he barely counts fingers. An afferent pupil defect is present in the left eye. This is what the left fundus shows. What is the diagnosis?

Review Topic

Correct. Giant cell arteritis is an autoimmune inflammation of medium-sized arteries, especially branches of the external carotid artery. Patients may report headache, scalp tenderness, and jaw claudication. If not treated, patients may develop sudden loss of vision in one eye. The unaffected eye is often affected soon afterwards. Examination will reveal an afferent pupillary defect and a swollen optic disc, as seen here. Patients require immediate intravenous corticosteroid treatment and a temporal artery biopsy.
Incorrect. Optic neuritis presents with painful vision loss. However, it is usually a diagnosis made in younger individuals and does not include pain on chewing. The optic disc abnormality you see here would not occur.
Incorrect. Papilledema is an important cause of a swollen optic disc. However, the swollen optic disc is usually found in both eyes and vision is relatively well preserved. The combination of symptoms and signs in this patient suggests an alternative diagnosis.
Incorrect. Infiltration of the optic nerve by cancer cells in the meninges can cause acute or subacute vision loss. However, the combination of symptoms and signs here suggests another diagnosis.