Glaucoma is a chronic eye disease affecting millions of people worldwide; it is frequently treated with daily eyedrop medications when patients are asymptomatic. Patient education is an essential feature for adherence to treatments. Developing useful patient education interventions is predicated on understanding what glaucoma patients know about their disease and identifying gaps in their knowledge. Thirteen studies that have measured and described glaucoma patient knowledge using questionnaires were identified from the literature, including cross-sectional studies of disease knowledge and studies evaluating the efficacy of an educational intervention, both randomized controlled and observational. All studies found significant knowledge gaps in glaucoma patients. Both the controlled studies and the observational studies supported the efficacy of various educational interventions for improving glaucoma knowledge.