Primary Open Angle Glaucoma (IMAGE) Cell Press Caption This is the optic nerve of a patient with primary open angle glaucoma, showing characteristic enlarged cup to disc ratio, excavation and loss of nerve fiber layer. Credit Image provided by Kang Zhang, MD, PhD Usage Restrictions Credit required License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.