Ronald S. Harwerth, University of Houston (IMAGE) University of Houston Caption Ron Harwerth, recipient of the 2011 Esther Farfel Award, uses this visual field tester in his work to test central and peripheral visual sensitivity to diagnose glaucoma or to determine the stage of the disease. Credit Thomas Campbell Usage Restrictions None 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.