A chronic disease, glaucoma affects about 60 million people worldwide and is a leading cause of irreversible vision loss. Initial treatment typically consists of medicated eye drops to lower internal eye pressure, yet up to half of glaucoma patients fail to fully benefit from these medications due to improper and/or inconsistent use. 

To help explain why glaucoma patient noncompliance happens, and what can be done to resolve it, a team of researchers at Romania’s Central Military Emergency Hospital examined the most relevant studies on glaucoma adherence.*

The importance of medication adherence

The goal of glaucoma treatment is to preserve a person’s remaining vision by lowering intraocular (internal eye) pressure, or IOP, to a level that won’t cause further damage to the optic nerve. To succeed, though, patients must strictly follow their medication program. While inconsistency with taking medication is not unique to glaucoma, the lack of noticeable symptoms in both open-angle glaucoma and normal-tension glaucoma (two of the most common forms of the disease), along with the absence of discernible improvement after long-term treatment, leaves glaucoma patients more vulnerable to treatment non-compliance.

Patterns of medication adherence (how do you compare?)

Research shows that people with chronic conditions fall into one of a half-dozen patterns of taking medication. These patterns include people who:

• Have near-perfect medication adherence
• Take nearly all medication doses but at inconsistent times
• Infrequently miss a medication dose and may be inconsistent with timing
• Take drug “holidays” three to four times a year and occasionally miss doses
• Take a drug holiday on a monthly, or more frequent, basis and often miss doses
• Take few or no medication doses, yet tell their clinicians they have good adherence

“Patients naturally want to please the doctor,” the authors write, “which makes them reluctant to admit nonadherence.”

What causes people to skip their medication?

The underlying reasons for people not adhering to glaucoma medication are complex, say the authors. To begin with, most people with glaucoma are older adults who may find it challenging to take any medications due to low vision and loss of manual dexterity. Because of this, they may rely on caregivers to apply their eye drops.

In studying barriers to glaucoma medication adherence, U.K. researchers found multiple obstacles, such as:

• Not having received initial instruction on how to apply the eye drops
• Problems with the regular scheduling of eye drops
• Forgetting doses
• Encountering eye drop supply issues

Other research linked nonadherence to medication storage requirements such as refrigeration.

The Glaucoma Adherence and Persistency Study

In The Glaucoma Adherence and Persistency Study (GAPS), possible barriers to medication adherence from the patient perspective were found to be:

• Cost 
• Forgetfulness 
• Fear or denial
• Lack of disease understanding
• Complexity of medication regimen

Perceived barriers to adherence from the physician perspective included:

• Lack of patient motivation and/or disease understanding 
• Physician’s inability to convey the importance of adherence 
• Limited time with patients 

Interestingly, several types of physicians were also identified:

• Skeptics were least likely to initially discuss glaucoma or the importance of disease treatment, believing it wouldn’t affect adherence.
• Reactives were least apt to sense and address nonadherence.
• Idealists were most likely to pursue patient adherence through methods such as explaining how to use eye drops and setting appointment reminders. 

What can be done to improve adherence detection?

Multiple ways of detecting nonadherence have been proposed, including:

• Measuring IOP over a 24-hour period
• Administering questionnaires
• Checking the rate of prescription refills
• Electronic medication monitoring (the most effective method)

The Travatan Dosing Aid is an example of electronic medication monitoring (for travoprost). The device holds the bottle in place, a lever is pressed to administer the drops, and an internal chip records the date and time. The Travatan Dosing Aid Study showed that, of 196 glaucoma patients, just 55% used their drops at least 75% of the time—despite knowing they were being monitored and given free medication. They also reported much higher use than the monitor reflected. Those with under 50% adherence took the most doses just before and after office visits.

What can be done to improve medication adherence?

To improve adherence, the authors say a multi-faceted approach seems needed, consisting of:

• Patient education
• Better doctor-patient communication
• Simplifying medication regimens
• Reducing medication costs
• At-home IOP monitoring

Studies show that adherence can markedly improve quality of life for glaucoma patients, and that not taking medication as prescribed increases the likelihood of unintended consequences like disease progression and higher healthcare costs. “Thus,” the authors conclude, “understanding factors associated with maintaining one’s medication regimen is important to patients and doctors.”

*Zaharia, A.-C., Dumitrescu, O.-M., Radu, M. & Rogoz, R.-E. (2022, April). Adherence to Therapy in Glaucoma Treatment—A Review. Journal of Personalized Medicine, 12(4), 514. https://doi.org/10.3390%2Fjpm12040514