Water Drinking Test Study and Disc Hemorrhages in Normal Tension Glaucoma

Inclusion Criteria: * Clinical diagnosis of normal tension glaucoma by a fellowship trained glaucoma specialist, * Clinical diagnosis of a disc hemorrhage diagnosed by a fellowship trained glaucoma specialist, * Must be able to swallow water * Must be able to be positioned to allow accurate measurement of the Intraocular pressure with a slit lamp mounted Goldmann applanation tonometer * Must have a smooth corneal surface to allow for accurate Goldmann application tonometry measurement * Outpatient * A sufficient level of education to understand study procedures and be able to communicate with site personnel Exclusion Criteria: * History of refractive surgery, * Active ocular infection, * Pregnancy, * Cardiac or renal diseases, history of urinary retention, * Corneal abnormalities preventing reliable IOP measurements, * Previous trabeculectomy or glaucoma shunt surgery, * Previous laser iridotomy, * Cognitive impairment or language barrier preventing ability to provide an informed consent.