TOPIC: Risk factors for poor adherence or nonadherence to topical glaucoma medication regimens. CLINICAL RELEVANCE: Poor adherence to glaucoma medication regimens may be associated with subsequent visual loss and irreversible optic nerve damage. METHODS: A literature search was performed using the words "glaucoma AND adherence AND risk" and "glaucoma AND compliance AND risk," limited to those studies in English and focused on care in the United States. Publications from well-regarded journals in this field were reviewed, and a focused summary of the literature is presented. RESULTS: There are a myriad of adherence barriers inherent to the glaucoma patient population. Although most of these obstacles are common in the elderly (e.g., reduced cognition, musculoskeletal problems, and transportation difficulties), older age has not been shown to be a consistent risk factor for poor adherence to glaucoma medication regimens. Other expected barriers, such as medication cost, limited health insurance, disease severity, and role of complicated dosing regimens, have varied effects based on the patient population studied and the definition of adherence. Poor medication adherence also is associated with decreased adherence to follow-up medical visit schedules. A systematic taxonomy of adherence barriers has been formulated. In addition, subanalyses from the Glaucoma Adherence and Persistency Study identified 8 variables that affect adherence to glaucoma medication regimens as well as several characteristics that support the importance of and associations between doctor-patient communications. CONCLUSIONS: Recent studies have provided valuable insights into the many factors that increase the risk(s) for poor adherence in patients prescribed glaucoma medications. Four major types of barriers to effective patient adherence (medication regimen, patient factors, provider factors, and situational or environmental factors) have been identified. Addressing these specific barriers will require a tailored, patient-centered approach. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.