Glaucoma is a group of eye diseases characterized by progressive and irreversible damage to the optic nerve. The aim of the study was to examine the impact of sociodemographic and psychological factors on adherence to glaucoma therapy. The study was carried out among 190 adults treated for glaucoma at the Ophthalmology Outpatient Clinic of the University Teaching Hospital in Wroclaw between January 2019 and September 2019. Treatment adherence was measured using the Adherence to Refills and Medications Scale (ARMS). We used the Acceptance of Illness Scale (AIS), the Revised Life Orientation Test (LOT-R) and the Satisfaction with Life Scale (SWLS). 58.9% patients reported low treatment adherence. Educated females aged 68 or under living in cities had higher adherence. The regression analysis showed an association between dispositional optimism and glaucoma treatment adherence. The higher the level of dispositional optimism, the better the adherence. Higher dispositional optimism is directly associated with a sense of self-esteem and self-efficacy and a feeling of internal control. Patients reporting a high level of illness acceptance were found to have 2.5 times higher odds of adhering to glaucoma therapy. Illness acceptance is an indicator of the degree of adaptation to an illness and is positively correlated with a sense of self-esteem and self-efficacy and engagement in healthy behavior. More than half of patients with glaucoma have low adherence. Sociodemographic characteristics (female gender, age 68 or under, tertiary education and living in an urban area) and psychological characteristics (high level of illness acceptance, dispositional optimism and satisfaction with life) are significant predictors of high adherence.