Can Visual Electrophysiology be Used to Screen Patients with Normotension Glaucoma

Normotension glaucoma (NTG) is a common form of primary open angle glaucoma where the intraocular pressure is not elevated (< 22mmHg) but there is chronic, progressive optic neuropathy with characteristic nerve head cupping, RNFL thinning and visual field loss. There are a number of conditions that can appear similar to NTG, particularly early on in the presentation when progression has not been established. Visual electrophysiology (Pattern visual evoked potentials (PVEP), flash VEP, Pattern electroretinogram (PERG), full-field ERG) can elucidate the source of visual loss. Abnormalities of the electroretinogram call into question the diagnosis of NTG. PVEP delay with or without accompanying N95 loss, seen in optic nerve disease, is not thought to be characteristic of glaucoma.