Glaucoma is the second leading cause of blindness in the world and has a significant economic impact on patients. Adherence to glaucoma treatment is a significant challenge in this disease population and results in the progression of the disease to more advanced and costly stages. Patient-physician communication has been associated with improved medication adherence in other chronic disease states. Previous studies have cited cost as a significant barrier to adherence in glaucoma patients, yet to date no published articles have examined the specific details of cost-related discussions between glaucoma patients and physicians. This dissertation is a secondary data analysis of patient interview data and videotape transcripts from glaucoma office visits. Data were collected from 6 ophthalmic sites across the United States from 2009-2012 and include 15 ophthalmologists and 279 glaucoma patients. Qualitative methods were employed to describe the medication cost discussions between glaucoma patients and their ophthalmologists. Logistic regressions were used to investigate the association between physician and patient characteristics and whether medication cost discussions occur. Logistic regressions were also used to examine the influence of patient-physician discussion of medication cost on medication adherence while controlling for a number of patient, physician, and medication characteristics. Results revealed that 31% of glaucoma office visits contained medication cost discussions. Patients that were new to glaucoma medications and reported it was hard to pay for their prescriptions were more likely to discuss medication cost. Physicians proposed a solution to a cost problem in 18% of visits while patients indicated cost was a problem in only 5% of visits. Patients who were new to glaucoma medications were less adherent to their glaucoma medications. Communication of medication cost did not significantly predict medication adherence. This study helps address gaps in the literature by improving our understanding of the extent and nature of patient-provider communication regarding medication cost. Our results have implications for the development of conceptual frameworks and interventions to improve patient-provider communication. Future work should further explore the role of patient-physician communication concerning medication costs on glaucoma patient outcomes.