04 Apr 2013, BioSpectrum Bureau , BioSpectrum
Singapore: A study conducted in mice by the National Institute of Health, US, has revealed that targeting cholesterol metabolism in the eye might help prevent a severe form of age-related macular degeneration (AMD). As a natural consequence of aging, cholesterol is known to accumulate in the eye within deposits called drusen leading to the development of AMD.
The disorder causes damage to the macula, a region of the retina responsible for central and high-resolution vision. The macula is dense with light-sensing cells called photoreceptors, and is what humans rely on for tasks that require sharp vision, such as reading, driving, and recognizing faces.
This sharp vision deteriorates in AMD, which can take two forms. In one, sometimes referred to as dry AMD, vision loss is due to a gradual loss of photoreceptors in the macula. In the other, referred to as wet or neovascular AMD, abnormal blood vessels grow under the macula, leaking blood and causing rapid damage to the photoreceptors.
An eye affected by neovascular AMD, filled with abnormal blood vessels and yellow deposits called drusen. The white spot at the right is where the optic nerve leaves the eye. Credit: National Eye Institute. What triggers neovascular AMD is unclear. Drusen, and the cholesterol within them, have been prime suspects. And based on genetic studies, including a recent genome-wide association analysis, the immune system appears to play a role, too. But researchers have had few details to connect these two pathways.
Dr Grace Shen, program director, National Eye Institute, NIH, US, which funded the research, said that, "This study points to a novel strategy for early intervention to prevent the progression of AMD to the severe neovascular form of the disease."