New Research Targets a Potential Cause of Dry Age-Related Macular Degeneration

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A consortium of research groups from Finland, Italy, Germany, Hungary, and Saudi Arabia have provided laboratory evidence (via cell cultures and human tissue samples) that the degenerative changes characterizing age-related macular degeneration (AMD) – specifically dry AMD, for which there is no current treatment or cure – are caused by impaired function of the body’s cellular “digestion” and “clean-up” mechanism, called autophagy, in the retina.

Autophagy, a basic biological and metabolic process, “self-eats” cellular components that are unnecessary or dysfunctional to the cell, such as those that can cause the degenerative retinal changes that accompany AMD.

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This intriguing laboratory-based study was published in the July 29, 2013 issue of PLoS ONE, an international, peer-reviewed, open-access online journal, published monthly by the Public Library of Science (PLoS). The PLoS is a non-profit organization of scientists and physicians who are committed to making the world’s scientific and medical literature a freely available public resource.

About Dry Macular Degeneration

The dry (also called atrophic) type of AMD affects approximately 80-90% of individuals with AMD. Its cause is unknown, it tends to progress more slowly than the wet type, and there is not – as of yet – an approved treatment or cure; however, there are clinical trials underway.

In dry age-related macular degeneration, small white or yellowish deposits, called drusen, form on the retina, in the macula – the small sensitive area in the center of the retina that provides clear central vision – causing it to deteriorate or degenerate over time.

Photograph of a retina with drusen

A retina with drusen

The drusen are the hallmark of dry AMD or macular degeneration. These small yellow deposits beneath the retina are a buildup of waste materials. They are made up of cholesterol, protein, and fats.

Typically, when drusen first form, they do not cause vision loss. However, they are a risk factor for progressing to vision loss. When a person has more advanced dry macular degeneration, there are many more of these small yellowish deposits and they are larger.

More about the Research

From Impaired Autophagy Associated with Age-Related Macular Degeneration in Science Daily:

AMD is a storage disease in which harmful protein accumulations develop behind the retina. These accumulations are indicative of the severity of the disease. As the disease progresses, retinal sensory cells in the central vision area are damaged, leading to loss of central vision. The cell biological mechanisms underlying protein accumulations remain largely unknown.

The present study showed that AMD is associated with impaired … autophagy, which is an important clean-up mechanism of the [retina]. This renders the cells in the [retina] unable to dispose of old, deformed or otherwise faulty proteins, which, in turn, leads to the development of protein accumulations and loss of vision.

The study can be regarded as a breakthrough, as the results change our understanding of the pathogenesis of AMD and also open new avenues for the treatment of the dry form of AMD. Drugs inhibiting the impairment of autophagy could possibly even stop the progression of AMD.

Conclusions from the Research

From the study authors’ discussion and conclusions:

Besides many recent advances in the understanding of autophagy mechanisms, it is now widely accepted that dysfunctions in these processes have a key role in many neurodegenerative diseases, including AMD.

Moreover, autophagy is increasingly emerging as a novel target of therapies aimed to counteract protein aggregation and improve cell viability; within this context, preservation of autophagy may protect [retinal] cells from degeneration and thus represents a potential tool to slow or even prevent the development of AMD.

VisionAware will continue to provide updates on this research as they become available.