Comparing SD-tVEP and PERG Tests Between Patients With Glaucoma, Patients With High Eye Pressure and "Normal" Patients

Glaucoma is the most common cause of irreversible blindness worldwide. It is characterized by the progressive loss of retinal ganglion cells (RGCs) and a corresponding loss of vision. Elevated intraocular pressure (IOP) is an important risk factor for glaucoma, but its role in the diagnosis of glaucoma is unclear. Although IOP-lowering therapy delays the onset of glaucoma in some patients with ocular hypertension, even without therapy, 90% of patients will not develop glaucoma over a 5-year period. Visual evoked potentials (VEPs) are able to detect the disruption of electrical signals at any point along the visual pathway, from the RGCs to the primary visual cortex. As an objective measure of visual function, the VEP may have an advantage over traditional visual field tests, by reducing confounded factors such as age, fatigue, and mental status. There is a growing body of evidence that SD-tVEP can objectively identify early visual dysfunction due to glaucoma. Aim 1: Compare the results of the baseline SD-tVEP and PERG vision testing in patients with ocular hypertension to a cohort of 30 healthy subjects and a cohort of 30 patients with glaucoma (of varying severity) to determine its ability to detect visual dysfunction in ocular hypertensive subjects. Aim 2: Conduct SD-tVEP and PERG testing system in 30 patients with ocular hypertension before and after IOP reduction with topical medication and compare the results of the SD-tVEP and PERG before and after treatment in each patient, to determine its ability to detect reversible RGC dysfunction.