A 62-year-old Asian man presents to the emergency department with a complaint of sudden visual impairment of his left eye for the past 5 days. The patient says he woke up with the impairment and had his normal baseline vision before going to sleep the evening before (he wears bifocal corrective lenses). He describes the impairment as “severe blurriness” and inability to see anything clearly in his entire visual field OS. He also reports his color vision being affected as well.
He denies eye pain, redness, discharge, recent trauma (either to his left eye or head), or right eye involvement. He also denies onset of any other new symptoms (including muscle weakness, paresthesias, facial involvement, headaches, dizziness, or recent syncopal episodes). When asked why he didn’t seek medical attention when he first noticed the visual change, he states he was hoping it would improve with time. He denies previous similar episodes.
His past medical history includes hypertension for which he takes lisinopril 20 mg at bedtime, and type 2 diabetes for which he takes metformin 1 g daily. He takes no other medications. He denies any past or present psychiatric illnesses. Past surgical history includes appendectomy at age 28 years. He is a nonsmoker, drinks alcohol socially, and denies illicit drug use. His family history is noncontributory. Other than his chief complaint, his review of systems is essentially negative.
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Physical Examination
On examination, his vital signs are normal. His visual acuity is 20/160 OS (previous medical record showed OS was 20/30 1 year ago) and 20/30 OD corrected. His extraocular muscles are intact and his intraocular pressure is measured via tonometry and found to be within normal limits at 15 mm Hg.
Table 1. Vital Signs
| Temperature | Afebrile |
| Pulse, beats per minute | 88 |
| Blood pressure, mm Hg | 140/82 |
| Respiratory rate, breaths per minute | 14 |
A visual field defect is found on the affected eye but the right eye is intact. The patient is found to have a relative afferent pupillary defect (RAPD), otherwise known as a Marcus Gunn pupil, in the left eye. Fundoscopic examination in the left eye revealed a small, hyperemic disc with indistinguishable borders. The right eye fundoscopic examination was negative as was the slit lamp examination bilaterally. The remainder of his physical examination, including a thorough neurologic examination, was negative.
Diagnosis
Because of several risk factors for ischemic stroke including diabetes and hypertension, computed tomography (CT) angiography of the brain is ordered and is negative. The patient is referred to the on-call ophthalmologist who diagnoses the patient with nonarteritic, anterior ischemic optic neuropathy (NAION). He is given the option of enrolling in an ongoing clinical treatment trial but declines as he does not want to receive intraoptic injections.
This article originally appeared on Clinical Advisor
