Photobiomodulation Therapy in Age-Related Macular Degeneration

Justin C. Muste; Aneesha Kalur; Amogh Iyer; Carolina C.S. Valentim; Rishi P. Singh

Disclosures

Curr Opin Ophthalmol. 2021;32(3):225-232. 

In This Article

Abstract and Introduction

Abstract

Purpose of Review: To review the available data supporting the use of photobiomodulation therapy (PBT) in the treatment of age-related macular degeneration (AMD).

Recent Findings: PBT might be used in treating nonexudative AMD. Limited evidence suggests that exudative AMD may also benefit from PBT.

Summary: The optimal device would deliver doses of 60 J/cm2 or more with a multiwavelength composition through the pupil over short treatment intervals. Safe upper limits have not been established. More studies are needed to evaluate the efficacy of PBT in treating exudative and nonexudative AMD.

Introduction

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in adults over 50 and constitutes a tremendous socioeconomic burden.[1] Three major pathophysiologic mechanisms for AMD have emerged. First, declining mitochondrial function and, by extension, ATP production with age reduced the ability of these organelles to fuel retinal tissue.[2] Second, cumulative retinal pigmented epithelium (RPE) oxidative stress and demand secondary to aging lead to dysfunction in the RPE's ability to support photoreceptors.[3] Third, mutations in the alternate pathway of the complement system in complement factor H, complement factor B, complement factor I, and complement factor 3 (C3) are associated with susceptibility to AMD.[4–6] These changes hamper the RPE's ability to nourish the retina, rendering the tissue ischemic and atrophic (nonexudative AMD). In some cases, ischemia leads to an imbalance between proangiogenic vascular endothelial growth factor (VEGF) and transforming growth factor beta and naturally retino-protective factors such as pigment epithelium-derived factor (PEDF).[7] Accordingly, pericyte depleted vessels invade the area, initiating a period of choroidal neovascularization and vision threatening complications (exudative AMD).

Anti-VEGF injections produce rapid anatomic response and improve visual acuity in exudative AMD.[1] However, no such treatments exist for nonexudative AMD. Even disease slowing age-related eye disease studies (AREDS) vitamin formulation is being called into question.[8] Photobiomodulation therapy (PBT) is an emerging therapy and shows potential both as a treatment for nonexudative AMD and an adjunct to the treatment of exudative AMD. This review article explores the mechanism of action and rationale for PBT treatment for both AMD variants. Optimal parameters and expected treatment outcomes for PBT will be discussed.

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