Is nonadherence with eye drop treatment associated with increased intra ocular pressure?

Purpose: Effectiveness of clinical glaucoma treatment may be dependent on the patient’s adherence (A) with eye drop treatment. The relation between non‐adherence (NA) and intraocular pressure (IOP) is not yet well understood, due to methodological weaknesses in the studies performed so far. The goal of this study was to investigate the association between NA with eye drop treatment, IOP and degree of visual field (VF) defects in a large sample of glaucoma patients. Methods: A multi‐center cross‐sectional survey was performed in 973 patients in 60 ophthalmologic centers in Belgium. NA was assessed by a written self‐report question asking patients how many times he/she had forgotten to administer eye drops during the past 2 weeks. Answer options ranged from never, seldom, once a week to daily. The patients indicating they had skipped 1 or more administrations were classified as NA. Current IOP (mmHg) and VF defects were measured with a Goldmann applanation tonometer and perimeter, respectively, at the same time as the NA assessment. Results: 603 out of 937 (64%) questionnaires were available for analysis. 39.5% of the patients reported to be NA. NA patients showed a significant higher current IOP of the left eye than A patients (16.12 +/‐ 3.15 vs 15.58 +/‐ 2.83; p=0.030). No significant difference in IOP of the right eye was found between NA and A patients (16.13 +/‐ 3.53 vs 16.02 +/‐ 7.61; p=0.843). The degree of visual field defects was not significantly related to NA. Conclusions: Because of the difference in IOP of the left eye between A and NA patients, NA should be carefully monitored as part of glaucoma management. Yet, prospective studies are needed to confirm the relationship between NA and poor outcomes.