Factors affecting eye drop instillation in glaucoma patients with visual field defect

BACKGROUND To investigate the success rate of eye drop instillation in glaucoma patients with visual field defect as well as non-glaucoma volunteers. Factors that may affect the success rate of eye drop instillation were also evaluated. DESIGN A prospective, observational study. PARTICIPANTS Seventy-eight glaucoma patients and 85 non-glaucoma volunteers were recruited in this study. METHODS Open angle glaucoma patients with visual field defect as well as non-glaucoma volunteers were asked to video record their procedures of eye drop instillation using a 5-mL plastic bottle of artificial tear solution. Success of eye drop instillation was judged on video based on the first one drop of solution successfully applied on the cornea, by two investigators. MAIN OUTCOME MEASURES Success rate of eye drop instillation in glaucoma patients and non-glaucoma volunteers. Factors related to success rate of eye drop instillation, such as visual field defect and clinical characteristics, were also analyzed using multivariable logistic regression. RESULTS No significant deference in mean age was observed between two groups (glaucoma: 64.5 ± 14.4 years, non-glaucoma: 60.9 ± 14.1 years, P = 0.1156). Success rate of eye drop instillation was significantly lower (P = 0.0215) in glaucoma patients (30/78; 38.5%) than in non-glaucoma volunteers (48/85; 56.5%). The most frequent reason of instillation failure in glaucoma patients was touching the bulbar conjunctiva, cornea, eyelid or eyelashes with the tip of the bottle (29.5%). Multivariable logistic regression analysis identified lower corrected visual acuity (VA) (≤ 1.0; odds ratio [OR] = 0.20, 95% confidence interval [CI] 0.04-0.93, P = 0.0411), lower mean deviation (MD) (< -12 dB; OR = 0.20, 95% CI 0.05-0.86, P = 0.0307) and visual field defect (VFD) in the inferior hemifield (OR = 0.11, 95% CI 0.02-0.34, P < 0.001) to be significantly related to instillation failure in glaucoma patients. CONCLUSIONS Success rate of eye drop instillation was significantly lower in glaucoma patients than in non-glaucoma volunteers. Corrected VA ≤ 1.0, MD < -12 dB and/or VFD in the inferior hemifield may be related to failure of eye drop instillation.