A survey of medical treatment patterns for primary open-angle glaucoma (POAG) was mailed to all United States members of the American Society of Cataract and Refractive Surgery (ASCRS) in March 1998; 21.2% responded. Demographic information pertinent to glaucoma care was also obtained. The use of diagnostic ancillary tests, as well as the sequential order of preferred therapy, in 3 hypothetical patient populations was analyzed: patients with mild, moderate, and advanced POAG. Preferred medical therapy was cross-tabulated with number of years in practice, fellowship training in glaucoma, and geographic location.