Around the world, glaucoma is a leading reason for irreversible blindness and its prevalence is rising. The number of people living with glaucoma globally is projected to rise from 64.3 million to 112 million by the year 2040. 

The most common treatment for glaucoma is medicated eye drops. Only about half of Americans adhere to their prescribed eye drop regimen, however, with even fewer sticking with it long-term. Research has shown 86% lower odds of moderate-to-severe visual impairment in glaucoma patients who take 80% or more of their medication. The Collaborative Initial Glaucoma Treatment Study (CIGTS)* explored glaucoma medication adherence and visual field test results for up to 10 years. Here is what researchers found.

What the researchers did

The CIGTS initially compared the effectiveness of eye drops to trabeculectomy in 607 new glaucoma patients. It then examined how medication adherence impacted vision in 307 of the patients randomly assigned to a separate medication study group.

• Participants were monitored for an average of 7.3 years at 6-month intervals.
• Self-reported medication use was analyzed, and visual field was measured, in 306 patients for whom adherence data were available.

What they found

As reported in the journal Ophthalmology, the results showed a significant association between medication noncompliance and glaucoma-related vision loss. Specifically:

• 164 of 306 patients (about 54%) reported missed medication doses during follow-up visits.

Of these 164 patients:

• 112 indicated a missed dose at as many as a third of follow-up visits.
• 31 indicated a missed dose at one- to two-thirds of visits.
• 21 indicated a missed dose at over two-thirds of visits.

Concerning visual field impact after eight (8) years:

• Of the 142 patients who reported never missing a dose of medication, estimated visual field loss was just 0.62 dB (decibels).

In contrast, estimated visual field loss in patients reporting missed medication doses was:

• 1.42 dB in the 112-patient group,
• 1.82 dB in the 31-patient group, and
• 2.23 dB in the 21-patient group.

What it means

In patients who never missed a medication dose, visual field loss was within the range of age-related vision loss in people with stable glaucoma: 0.05 dB to 0.1 dB per year.

That said, the authors explain in Ophthalmology, CITGS participants were “quite adherent” to both their eye medication and follow-up visits overall, and the result of the study “likely underestimates the true magnitude of the association between medication adherence and visual field progression.”

The authors conclude that “a critical need exists to focus on helping to support patients with improving glaucoma medication adherence.” In turn, this could improve the effectiveness of medications already in use.

*Linnehan, R. (2020, May 28). Medication adherence, visual field loss significantly associated. Healio. https://www.healio.com/news/ophthalmology/20200528/medication-adherence-visual-field-loss-significantly-associated