Dorzolamide-timolol in Combination With Anti-vascular Endothelial Growth Factor Injections for Wet Age-related Macular Degeneration

Overview

A previous pilot study demonstrated that commonly available glaucoma drops (dorzolamide-timolol) might decrease the amount of chronic swelling in patient with wet age-related macular degeneration who have been receiving anti-vascular endothelial growth factor (VEGF) injections. This will be a larger study where subjects are randomly assigned to receive the glaucoma drops or a placebo (artificial tears) in order to confirm whether this previous finding is valid. Subjects will continue to receive the normally scheduled anti-VEGF injections at regular intervals as done prior to enrollment. The only addition to the regimen will be the daily use of eye drops (dorzolamide-timolol or artificial tears) twice daily for the duration of the study. At the end of the study, the swelling in the retina will be compared to the amount before starting the drops to see if there is any difference between the group using dorzolamide-timolol versus artificial tears.

Intravitreal anti-vascular endothelial growth factor (VEGF) agents, including ranibizumab and aflibercept, remain the standard of care treatment for neovascular age-related macular degeneration (AMD). Various treatment modalities using these agents have been proposed, including monthly, pro re nata, and treat-and-extend regimens. Despite frequent and consistent treatment with anti-VEGF therapy, there is a subset of patients who are incomplete responders and have persistent exudation, including intraretinal edema, subretinal fluid (SRF), and/or retinal pigment epithelial detachment (PED) on spectral-domain optical coherence tomography (SD-OCT). While clearance of intravitreal anti-VEGF drugs is not completely understood, some studies have suggested that outflow through the anterior chamber may play a role. We hypothesized that by decreasing aqueous production, outflow may also be reduced which could subsequently slow the clearance of intravitreal drugs. In a prior pilot study with 10 eyes of 10 patients who were incomplete responders with neovascular AMD, the effect of topical dorzolamide-timolol in combination with continued intravitreal anti-VEGF injections was explored. Patients were kept on the same anti-VEGF drug as well as the same interval between injections for the 2 visits before enrollment and through the course of the pilot study in order to minimize the chances that any changes noted might be the result of altering one of these variables. The mean central subfield thickness (CST) decreased from 419.7 μm at enrollment to 334.1 μm at the final visit (p=0.012). Mean maximum subretinal fluid (SRF) height decreased from 126.6 μm at enrollment to 56.5 μm at the final visit (p=0.020). This decrease in mean CST and SRF was significant beginning at the first visit after initiation of the drops. Based on this initial pilot data, dorzolamide-timolol appears to be a promising adjuvant treatment in combination with anti-VEGF injections for incomplete anti-VEGF responders with neovascular AMD. However, since there was no control group in the pilot study, it is possible that the decreased exudation seen was a result of the continued anti-VEGF therapy alone rather than an effect of the topical therapy. As a result, a randomized, placebo-controlled clinical trial will be better able to assess the efficacy of dorzolamide-timolol in this setting.