Survival of medical treatment success in primary open-angle glaucoma and ocular hypertension

Abstract

Background/aims: Topical agents to lower intraocular pressure (IOP) are the most common initial therapeutic measure in glaucoma prevention. This study aims to assess treatment success duration among patients initiating or intensifying topical glaucoma medication.

Methods: Medical records (2013‒2018) for adults initiating/intensifying topical glaucoma medication were extracted from five secondary-care and tertiary-care UK ophthalmology centres. Main study outcomes were time from treatment initiation/intensification to treatment failure (<20% IOP reduction or IOP >21 mm Hg at consecutive clinic visits, or intensification of glaucoma treatment) and time from treatment change to subsequent treatment intensification.

Results: Study eyes (n=6587) underwent treatment intensification 0-to-1 glaucoma drop (5358 events), 1-to-2 drops (1469 events) and 2-to-3 drops (857 events) during the observation period. Median time to treatment failure was 1.60 (95% CI 1.57 to 1.65), 1.00 (95% CI 0.94 to 1.07) and 0.92 (95% CI 0.81 to 1.02) years following escalation 0-to-1, 1-to-2 and 2-to-3 drops, respectively. Median time to treatment intensification (non-IOP-based criterion) was 4.68 (95% CI 4.50 to 5.08) years for treatment initiators, 3.83 (95% CI 3.36 to 4.08) years on escalation 1-to-2 drops and 4.35 (95% CI 3.82 to 4.88) years on escalation 2-to-3 drops. On multivariable regression, significant risk factors for both treatment failure and intensification were lower baseline visual field mean deviation, primary open-angle glaucoma and lower eyedrop count in the fellow eye; lower baseline IOP was associated with treatment failure, higher baseline IOP with treatment intensification.

Conclusion: Large-scale survival analyses provide the expected duration of treatment success from topical glaucoma medication.

Keywords: Glaucoma; Treatment Medical.

Figure 1. Kaplan-Meier curve of time to inadequate intraocular pressure (IOP)-lowering effect following topical glaucoma treatment initiation or intensification. Kaplan-Meier estimates of reaching inadequate IOP-lowering effect, defined as time to: IOP reduction <20% at two consecutive visits; or IOP >21 mm Hg at two consecutive visits; or medication Intensification; or IOP-lowering glaucoma procedure. Treatment events considered were as follows: escalation from 0 to 1 class of topical glaucoma medication (treatment initiation; blue); from 1 to 2 classes of medication (red) and from 2 to 3 classes of medication (green). Median outcome time and the 95% CI are displayed here for each cohort.

Figure 2. Kaplan-Meier curve of time from treatment initiation (escalation from 0 to 1 class of topical glaucoma medication (treatment initiation; blue)) or intensification (escalation from 1 to 2 classes of medication (red) and from 2 to 3 classes of medication (green)) to subsequent treatment intensification. Treatment intensification was defined as an increase in the number of medical glaucoma agents or intraocular pressure-lowering procedure conducted.