Inverted Follicular Keratosis

Shortly after awakening, an 82-year-old man with a history of cataracts in both eyes noticed a sudden painless diminution of vision in the left eye. He had no new headaches or jaw claudication. His medications included hydrochlorothiazide and atorvastatin.

The patient's best corrected visual acuity was 20/25 in the right eye and 20/60 in the left. There was no afferent pupillary defect. The slit-lamp evaluation identified mild to moderate nuclear sclerotic cataracts. The fundus of the right eye was unremarkable. The optic disc of the left eye showed edema with blurred disc margins. The rest of the fundus of the left eye was normal.

A diagnosis of ischemic optic neuropathy (ION) was made. It is imperative to differentiate between arteritic ION (temporal arteritis) and nonarteritic ION. Temporal arteritis may lead to bilateral blindness if not treated promptly. Results of immediate evaluations of erythrocyte sedimentation rate and C-reactive protein level were normal. These results, as well as the absence of headaches and jaw claudication, supported the diagnosis of nonarteritic ION.

This condition is seen in elderly patients who have a systemic disorder such as hypertension, diabetes, hyperlipidemia, or generalized arteriosclerosis. A compromised autoregulatory mechanism at the anterior aspect of the optic nerve head results in decreased blood flow and ischemia. Patients experience a sudden, painless monocular loss of vision. Disc edema, often sectoral with a corresponding altitudinal visual field loss, is common during the acute phase. Optic atrophy develops in 4 to 6 weeks.

No treatment is available for nonarteritic ION. Systemic diseases should be identified and treated.