When 'Glaucomatous Fields' Are Not Glaucoma: Bilateral Calcarine Fissure Strokes Masquerading As Glaucoma In A Normal Tension Glaucoma Suspect

A 78-year-old man with vascular risk factors and a family history of glaucoma presents with bilateral superior arcuate visual field loss. MRI brain was reported normal. Intraocular pressure (IOP) and optical coherence tomography of the retinal nerve fibre layer (RNFL) were within normal limits. A tentative diagnosis of normal tension glaucoma was made. Over the next 5years, IOP remained stable without treatment, serial visual fields noted repeatable bilateral superior depressions with normal RNFL. Referral to a glaucoma subspecialist and subsequently neuro-ophthalmologist prompted repeat MRIs, which demonstrated mild small vessel ischaemia. Standard visual evoked potentials (VEPs) were normal. Multifocal VEPs identified poor response across the entire visual field in both eyes. The combination of visual defects, unremarkable RNFL and reduced multifocal VEPs raised suspicion of bilateral inferior calcarine fissure change. Retrospective review of MRI's in a multidisciplinary meeting confirmed extensive microvascular changes with bilateral inferior calcarine fissure ischaemia.