Ockham's glaucoma.

The combination of characteristic optic nerve head cupping, arcuate visual field loss and ocular hypertension would usually be thought sufficient to diagnose glaucoma. Only in the absence of elevated intraocular pressure, when normal tension glaucoma may be suspected, would intracranial imaging normally be performed to exclude occult pathology. A case is presented which illustrates the continuing need for vigilance, and an open mind, years after an apparently straight-forward diagnosis has been made.