Geographic atrophy, an advanced form of AMD, is characterised by atrophic lesions that first start in the outer retina and progressively expand to cover the macula and the fovea – the centre of the macula – leading to irreversible loss of vision over time. 

Looking to determine whether a daily supplement consisting of vitamins C and E, lutein, zeaxanthin, zinc, and copper – long recommended as an approach for earlier stages of the disease – could slow the progression of geographic atrophy, researchers reviewed the retinal scans of participants in the Age-Related Eye Diseases Studies (AREDS and AREDS2).

They found that, for people with late-stage dry AMD, taking the formula slowed expansion of geographic atrophy regions towards the central region of the retina.

“We’ve known for a long time that AREDS2 supplements help slow the progression from intermediate to late AMD. Our analysis shows that taking AREDS2 supplements can also slow disease progression in people with late dry AMD,” said lead author Tiarnan Keenan, from the National Institutes of Health (NIH) National Eye Institute, in the US.

“These findings support the continued use of AREDS2 supplements by people with late dry AMD.” 

Antioxidant supplementation halves rate of geographic atrophy expansion

In early and intermediate AMD, the light-sensing retina at the back of the eye develops small deposits of fatty proteins called drusen. When the disease progresses to the late stage, people can develop leaky blood vessels (wet AMD) or lose regions of light-sensitive cells in the retina (dry AMD).

The geographic atrophy in these regions slowly expands over time, causing people to progressively lose their central vision.

More than eight million people worldwide are affected by geographic atrophy – approximately 20% of all individuals with AMD. The incidence of the disease is expected to rise as the age burden of developed countries continues to increase.

Currently, the only treatments approved to slow progression of the disease are costly, require frequent intraocular injection, and display only modest efficacy, according to the study authors.

In their new analysis, published in the journal Ophthalmology, the researchers reviewed the retinal scans of participants in the AREDS (318 participants, 392 eyes) and AREDS2 (891 participants, 1,210 eyes) trials who developed dry AMD.

They examined the position and expansion rate of geographic atrophy regions. For participants who developed geographic atrophy in their central vision, supplementation had little benefit.

But for most people who developed geographic atrophy far from the fovea, the supplements slowed the rate of expansion towards the fovea by approximately 55% over an average of three years. 

Refining the formula: Accounting for ‘foveal sparing’

The original AREDS trial found that a supplement formula containing antioxidants (vitamins C and E, and beta-carotene), along with zinc and copper, could slow progression of intermediate- to late-stage AMD.

The subsequent AREDS2 trial found that substituting the antioxidants lutein and zeaxanthin for beta-carotene improved the supplement’s efficacy and eliminated some risks.

At the time, neither trial detected any further benefit once participants had developed late-stage disease. However, that analysis did not account for a phenomenon in this form of AMD called “foveal sparing”. 

Many people with dry AMD first develop geographic atrophy outside the foveal region, and only lose their central vision when the atrophy regions expand into the foveal area – the region with the highest-acuity central vision. 

“Our high-acuity central vision is essential for tasks like reading and driving,” said Keenan. “Given that there are few therapeutic options for people with late-stage dry AMD to retain or restore their vision, antioxidant supplementation is a simple step that may slow central vision loss, even for those with late disease.

“We plan to confirm these findings in a dedicated clinical trial in the near future.”