Factors Associated with Topical Medication Instillation Failure in Glaucoma: VRAMS-QPiG Study

INTRODUCTION: To report eyedrop instillation techniques and factors associated with instillation failure among glaucoma subjects in the Video-Recorded Assessment of Medication Skill and Questionnaire-based evaluation of Perception in Glaucoma Study. METHODS: In this cross-sectional observational study, subjects were 60 patients with glaucoma (mean ± standard deviation age, 68.4 ± 11.3 years; 30 men) who required ocular hypotensive medication(s). Subjects completed ophthalmologic examinations and the Mini-Cog cognitive function test; their typical eyedrop instillation technique was video-recorded. Subjects rated their technique as successes/failures by questionnaire and two examiners rated the successes/failures based on video assessment. Discrepancy between self-reported and video-assessed success/failure rates of instillation was the main outcome measures. Multivariate logistic regression identified factors in instillation failure. RESULTS: Of 48/56 (86%) self-reported successes, 27/48 (56%) failed based on video assessment; as a result, 32/56 (57%) were inconsistent between subjective and objective assessments. Overall, 30/56 (54%) failed based on video assessment. In the subject-based data model, older age [odds ratio (OR) 0.93/year, P = 0.025] and lower cognitive function score (OR 2.7/score, P = 0.025) were factors in failed instillations. In the eye-based data model, less myopic objective refractive error (OR 0.77/diopter, P = 0.016) and lower visual field foveal threshold (OR 1.1/decibel, P = 0.041) were factors in failures. CONCLUSION: In addition to older age, decreased cognitive function, hyperopia, and decreased foveal sensitivity are risks for failed eyedrop instillation. Treating physicians can screen patients who require guidance by checking the risk factors of instillation failure rather than by relying on patient reports.