Role of Metformin in the Development and Progression of Age-Related Macular Degeneration

Abstract

Purpose : Age-related macular degeneration (AMD) is a leading cause of irreversible blindness with limited treatment and management options. Metformin has been shown to have immunomodulatory roles which could influence the pathogenesis of AMD. This study investigates whether metformin confers a protective effect in delayed onset and slower progression of AMD.

Methods : This is a single-center retrospective cohort study, which included 18,431 patients aged 50-80 years, visiting ophthalmology clinics from September 2006 to August 2019. Among these, 132 patients with concurrent diagnoses of AMD and diabetes were further analyzed, stratified by metformin use. Data included demographics, presence and type of AMD, examination findings including visual acuity (VA), ocular coherence tomography (OCT) features and anti-VEGF injection frequency. These were compared between patients prescribed or not prescribed metformin.

Results : Among the 18,431 study patients, the average age was 63.7 ± 8.2 years in the metformin group and 63.0 ± 8.5 years in the non-metformin group (P = 0.0002). 74.6% of the metformin group had diabetes, compared to 9.3% of the non-metformin group (P < 0.0001). Incidence of AMD during the study period (4.2% compared to 5.1%, P = 0.049) and prevalence of AMD at the final visit (6.9% compared to 8.4%, P = 0.015) were found to be significantly lower in the metformin group compared to the non-metformin group. Several analyses were performed in a subset of 132 patients with concurrent diagnoses of AMD and diabetes. The metformin group exhibited less decline in VA (0.009 ± 0.041 logMAR/year), compared to the non-metformin group (0.013 ± 0.041 logMAR/year, P = 0.29) and less expansion of the area of geographic atrophy measured on OCT over time (1.10 ± 1.08 mm^2/yr), compared with the non-metformin group (1.66 ± 1.94 mm^2/yr, P = 0.33); however, these did not reach the level of statistical significance. A similar number of intravitreal anti-VEGF injections was required in the metformin group (2.2 ± 3.2 injections/year), compared with the non-metformin group (1.6 ± 2.1 injections/year) (P = 0.39).

Conclusions : Our data suggest that metformin may confer a protective effect against the onset and progression of dry AMD, though this protective effect may not apply to wet AMD.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.