Patient with normal tension glaucoma under the care of a fellowship trained glaucoma specialist and noted to have a disc hemorrhage in one or both eyes when examined in the office will be recruited to undergo a water drinking test (WDT). After an informed consent is obtained, arrangements will be made to undergo the WDT either at the ophthalmologist's office or the local hospital clinic(Misericordia). The test will be administered in the following way:~Upon arrival the patients baseline intraocular pressure (IOP) will be measured, then shortly afterwards the patient will drink 800 ml of water in a period of 5 minutes. Immediately after the water ingestion has finished a second IOP will be measured, followed by IOP measurements every 15 minutes for 60 minutes with a Goldman applanation tonometer by the same examiner. All of these measurements will be collected in a data sheet for the WTD. A total of 60 minutes would be the duration of the activity.
Disc hemorrhages are a known risk factor for progression of glaucoma. A positive water drinking test is also associated with progression of primary open glaucoma. The purpose of this study is to determine if patients with normal tension glaucoma and disc hemorrhages have a positive water drinking test.~Patients with normal tension glaucoma and a disc hemorrhage will be recruited to undergo a water drinking test prior to any change in their treatment.