Age-related Macular Degeneration

Current Treatment and Future Options

Tanya Moutray; Usha Chakravarthy

Authors and Disclosures

Abstract and Introduction

References

Abstract and Introduction

Abstract

Age-related macular degeneration is the leading cause of visual impairment among older adults in the developed world. Epidemiological studies have revealed a number of genetic, ocular and environmental risk factors for this condition, which can be addressed by disease reduction strategies. We discuss the various treatment options for dry and exudative age-related macular degeneration available and explain how the recommended treatment depends on the exact type, location and extent of the degeneration. Currently, vascular endothelial growth factor (VEGF) inhibition therapy is the best available treatment for exudative age-related macular degeneration but is limited by the need for repeated intravitreal injections. The current treatment regime is being refined through research on optimal treatment frequency and duration and type of anti-VEGF drug. Different modes of drug delivery are being developed and in the future other methods of VEGF inhibition may be used.

Introduction

Age-related macular degeneration (AMD) is the leading cause of visual impairment among older adults in the developed world [Klein et al. 1992]. Late clinical findings in AMD include geographical atrophy and neovascular AMD (nvAMD). It is estimated that a quarter of a million older adults in the UK are blind as a result of late AMD [Owen et al. 2003].

The pathophysiology of AMD includes diffuse thickening of the inner aspect of Bruch's membrane associated with soft drusen and may be accompanied by abnormalities of the retinal pigment epithelium (RPE) with focal hyperpigmentation. In patients with early AMD, visual function is good unless central geographical atrophy or nvAMD develops. Studies of the natural history show that severe visual loss, which is defined as a reduction of more than six lines of Snellen acuity, occurs in 21.3% of AMD patients at 6 months and 41.9% by 3 years [Wong et al. 2008]. The presence of large soft drusen and focal hyperpigmentation markedly increases the risk of developing late AMD [Cukras et al. 2010].

In exudative nvAMD, three patterns of choroidal neovascularization (CNV) have been defined: growth into the plane between the RPE and Bruch's membrane (type 1); growth between the retina and RPE (type 2); and retinal angiomatous proliferation within the retina (type 3). Blood and serum leak from these fenestrated vessels and cause separation of Bruch's membrane, the RPE and the retina from each other, leading to the accumulation of intraretinal fluid. This results in generalized thickening of the retina or the formation of cystic spaces, causing the photoreceptors to become misaligned, and eventually degenerative changes occur with cell loss and eventual fibrosis.

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