Purpose: Many glaucoma eye drop users cannot successfully self-administer drops, and observing patients' drop technique can be time-consuming. We sought to examine the association of patient self-reported efficacy of eye drop technique and medication possession data as potential surrogate measures for actual drop administration success.
Patients and methods: In total, 137 adults with medically treated glaucoma were enrolled from a University eye clinic (n=54) or a Veteran Affairs (VA) eye clinic (n=83). All participants were asked, "How confident are you that you can get the medication into your eye?" Medication possession ratio (MPR), defined as the amount of eye drop available divided by the amount prescribed, was calculated for VA study site participants for 6 months. The main outcome was the correct eye drop technique, defined as the ability to get drops into the eye and to put only 1 drop into the eye at a time.
Results: Among 117 participants who were "very confident" they could administer eye drops correctly, 95 participants (81%) displayed the correct drop technique. Of those who reported being less than "very confident" (n=18), 11 participants (61%) displayed correct drop technique (the Fisher exact test, P=0.07). For the VA sample, 20 participants with MPR<1.2, 20 participants with MPR=1.2 to 1.8, and 23 participants with MPR>1.8 displayed correct eye drop technique (the Fisher exact test, P=0.18).
Conclusions: Self-reported administration success and MPR are not strongly associated with successful eye drop administration. Thus, direct observation of patients' drop instillation may be the most effective means of determining patient efficacy.