Extraordinary progress has been made over the last 5 years in improving our understanding of the molecular causes of various glaucomas. Identification of the myocilin gene and of 5 additional genetic loci that play a role in development of primary open angle glaucoma provides us with an opportunity to reclassify this complex phenotype based on underlying cause of disease. Clinicians who obtain a detailed family history from their patients and who have referred families with glaucoma to laboratory investigators are at the forefront of this revolution in molecular genetics. As a result, all clinicians will soon be poised to profit from genetic discoveries by being able to order diagnostic tests that will identify specific genetic mutations. These mutations will provide a detailed understanding of the natural history of the patient's glaucoma, as well as information for genetic counseling. Individuals at risk in the family will be able to be identified, permitting closer follow-up and earlier institution of glaucoma therapy. A new understanding of pathophysiology is developing and will provide the basis for more rational pharmacological and gene therapy approaches in the future. The hope of primary prevention for various glaucomas, once a distant dream, may become reality within our lifetimes.