Eye Drop Adherence: Waste, Contamination, Inaccuracy

Studies investigating the problem of poor adherence to glaucoma medication administered in eye drops find a variety of culprits.

Adherence is a problem with many medications, but can be particularly challenging when chronic use is required. In this case, it can drop to between 50% and 80% within 6 months to a year. When the medication is in the form of an eye drop, adherence can be complicated by factors including manual dexterity, cognition, and medication cost. Poor adherence to topical ophthalmic products creates a tremendous risk for glaucoma patients—it may lead to blindness.

Several recent studies have examined adherence issues among glaucoma patients with interesting results.

In a study published in the December 2011 issue of the American Journal of Ophthalmology, researchers used video cameras to monitor drop instillation in 406 patients with disease-induced pre-existing visual impairment—some due to glaucoma and some due to retinal disease. They found that approximately one-third of the patients in each group were unable to place an eye drop into the eye. The patients contaminated eye drop bottle tips, wasted drops, and overestimated their ability to instill drops. As patients aged, their technique declined. The authors suggested that replacing topical medication with other administration routes could be an option for improving care in the future.

“Poor patient adherence, even if unintentional, can have adverse effects on a person's response to therapy, as well as their disease progression,” the researchers write. “The group that may most need and may be most persistent with therapy is the group with the greatest visual impairment. Although those who are visually impaired may be more motivated, they in fact may have more difficulty administering eye drops.”

In a study published online on March 8, 2012, in the Journal of Glaucoma, researchers looked at adherence in a population of glaucoma patients using prostaglandin monotherapy. They randomized 38 patients to an intervention group and 42 patients to a nonintervention group. For 5 months, patients in the intervention group received automated telephone reminders to instill their glaucoma medications. In the third month of the study, patients in the intervention group received an educational briefing about their disease and treatment at their physicians’ offices. Patients in the nonintervention group received no reminders or targeted education. Adherence and therapeutic coverage was measured in both groups using an electronic monitoring cap. In addition, each patient completed the Minnesota Multiphasic Personality Inventory-2.

The results showed no increase in adherence for those in the intervention group. In fact, mean adherence in the intervention group was 76%, compared with 81% for those in the nonintervention group, although the difference was not statistically significant. For those in the intervention group, adherence did not change significantly after the educational briefing. However, patients who scored high on depression and hypochondriasis were significantly more likely to have lower adherence.

Finally, 2 studies have looked at adherence to glaucoma medications during admission to hospitals for other, non-ophthalmic diagnoses. The results of 1 study, published in the June 2010 issue of the Journal of the Royal Society of Medicine Short Reports, found that physicians forgot to write orders for glaucoma medications for about 60% of glaucoma patients admitted to a hospital. The authors of another study, published in the December 2011 issue of the Journal of Glaucoma, examined patient records over a 3-year period and found that slightly more than half of patients did not receive their glaucoma medications, with three-fourths of those omissions due to a physician’s failure to prescribe the eye drops.

Pharmacists can help improve adherence among glaucoma patients in several ways. They can demonstrate proper instillation technique each time a patient presents a new prescription, and observe the patient applying drops. Pharmacists should also remind patients to include eye drops on their medication lists, and insist that they need them if they are hospitalized. Encouraging patients to have a caregiver instill the drops is also prudent.

Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.