Glaucoma Medication Adherence:  Room for Improvement in Both Performance and Measurement

Glaucoma is the leading cause of irreversible blindness worldwide^1- 2 and the number of Americans with glaucoma is expected to increase by 50% in the next 15 years.³ Multiple clinical trials have shown that with effective medical treatment, much (but not all) vision loss can be prevented.^4- 6 Whether measured by pharmacy data,⁷ self-report,^8- 9 or medication monitor,¹⁰ adherence to glaucoma medication is often poor. Investigators studying medication adherence have identified multiple factors related to poor adherence, including more frequent¹¹ and complex¹² dosing and situational factors, such as competing activities¹² and forgetfulness,⁸ as well as patient-centered factors, such as poor disease knowledge,¹³ poor health literacy,¹⁴ and a passive learning style.¹³ This information is important because the identification of barriers to adherence facilitates a better understanding of the problems and possible interventions to reduce these barriers. However, to critique the success or failure of such interventions, we need to use comprehensive and accurate measurements of adherence. In this editorial, we have attempted to construct a framework for the components of medication adherence and review the metrics available for quantifying adherence.