City Research Online

Abstract

Background
Poor adherence to intraocular pressure (IOP)-lowering medication remains a major challenge in glaucoma care, contributing to avoidable vision loss. Existing adherence interventions are limited and often lack a robust theoretical foundation. With the growing global burden of glaucoma, there is a pressing need for scalable, effective, evidence-based interventions that are responsive to patients’ needs. This thesis adopts a behavioural science approach to develop a patient-level intervention, following UK Medical Research Council (MRC) guidance for complex intervention development. A structured process was followed: understanding the behaviour, identifying influencing factors, and determining what needs to change to support improved adherence.

Objectives:
• Identify key behavioural determinants of glaucoma medication adherence from the literature
• Develop a practical definition of acceptable adherence among UK glaucoma eye care professionals (ECPs)
• Identify modifiable behavioural determinants from the perspectives of patients and ECPs
• Develop a conceptual model for a theory-based, patient-centred intervention

Methods
A systematic review identified modifiable behavioural determinants, mapped to the Theoretical Domains Framework (TDF). A Delphi consensus study with UK ECPs was conducted to establish a benchmark for acceptable adherence to guide when intervention support should be triggered. Qualitative interviews with patients and ECPs explored real-world barriers and enablers, analysed using the TDF. Findings were synthesised to generate a behavioural diagnosis using the COM-B model (Capability, Opportunity, Motivation–Behaviour), informing the selection of relevant Intervention Functions (IFs) and Behaviour Change Techniques (BCTs) via the Behaviour Change Wheel (BCW). Selected components were integrated into a conceptual intervention model and evaluated for acceptability by key stakeholders.

Results
The systematic review and interview findings revealed three overarching patient-level barriers to adherence: (1) lack of understanding regarding glaucoma and/its treatment, (2) issues with eyedrop administration, (3) difficulties obtaining medication. These mapped to psychological capability, physical capability, and physical opportunity within the COM-B model. The Delphi study found that 80% adherence was generally considered acceptable for most glaucoma patients, with flexibility for clinical discretion. This threshold informed when intervention support should be activated. The behavioural diagnosis informed the selection of three IFs and seven BCTs, which were integrated into the Adherence Resources Toolkit (ART), a personalised adherence support toolkit. Stakeholder feedback indicated high acceptability and strong potential for the ART.

Conclusion
This thesis presents the first behaviourally informed, stakeholder-driven model designed to support glaucoma medication adherence. It provides a robust theoretical and empirical foundation for future feasibility testing and implementation in real-world clinical practice.

Publication Type:	Thesis (Doctoral)
Subjects:	R Medicine R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine R Medicine > RE Ophthalmology
Departments:	School of Health & Medical Sciences > Department of Optometry & Visual Science School of Health & Medical Sciences > School of Health & Medical Sciences Doctoral Theses Doctoral Theses

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