Electrophysiological approaches for early detection of glaucoma

PURPOSE. While elevated intraocular pressure (IOP) is a major risk factor f or glaucoma, only about 1 % of patients with 25 mmHg develop the condition each year. Since a sizeable proportion of the ganglion cells are already lo st when the visual field losses are apparent, the aim is to identify patien ts with elevated IOP in whom glaucoma damage is incipient before visual fie ld changes occur. METHODS. This report concerns early diagnosis of glaucoma with electrophysi ological techniques, rather than with monitoring the disease using various available psychophysical and morphological methods. Visual electrophysiolog y offers a wide range of tools to assess function layer-by-layer along the visual pathway. Their clinical value for early detection of glaucoma will b e discussed. The pattern electroretinogram (PERG), a direct functional indi cator of retinal ganglion cell function, is markedly affected by glaucoma, and in longitudinal studies the PERG correctly indicated eyes at risk befor e manifest glaucoma occurred. CONCLUSIONS. Consequently, this report will concentrate on the PERG. Less p roven, but promising measures like the "photopic negative response", the mo tion visually evoked potential (VEP) and the multifocal VEP will also be to uched upon.