Barriers and enablers to medication adherence in glaucoma: A systematic review of modifiable factors using the...

Nonadherence to medication reduces treatment effectiveness, and in chronic conditions it can significantly reduce health outcomes. In glaucoma, suboptimal adherence can lead to sight loss, which places a greater financial burden on society and reduces patients' quality of life. Interventions to improve adherence have so far had limited success and lack robust theoretical underpinnings. A better understanding of the determinants of medication adherence behaviour is needed in order to develop interventions that can target these factors more effectively. This systematic review aims to identify modifiable barriers and enablers to glaucoma medication adherence and identify factors most likely to influence adherence behaviour.

We searched CINAHL, MEDLINE, PsycINFO, EMBASE, the Cochrane Library and sources of grey literature up to August 2022 for studies reporting determinants of glaucoma medication adherence. Data describing modifiable barriers/enablers to adherence were extracted and analysed using the Theoretical Domains Framework (TDF), a behavioural framework consisting of 14 domains representing theoretical factors that most likely influence behaviour. Data were deductively coded into one of the TDF domains and inductively analysed to generate themes. Key behavioural domains influencing medication adherence were identified by frequency of study coding, level of elaboration and expressed importance. Eighty-three studies were included in the final synthesis. Four key domains influencing glaucoma medication adherence were identified: 'Environmental Context and Resources', 'Knowledge', 'Skills' and 'Memory, Attention and decision processes'. Frequently reported barriers included complex eyedrop regimens, lack of patient understanding of their condition, forgetfulness and difficulties administering eyedrops. Whereas simplified treatments, knowledgeable educated patients and good patient-practitioner relationships were enablers to adherence.

We identified multiple barriers and enablers affecting glaucoma medication adherence. Four theoretical domains were found to be key in influencing adherence behaviour. These findings can be used to underpin the development of behaviour change interventions that aim to improve medication adherence.