Stories about: Lois Smith

Age-related macular disease: Is energy starvation a cause?

age-related macular degneration
Hunger distress signal: Energy-starved photoreceptor cones in the retina (colored blue) call for nourishment by releasing a cloud of vascular endothelial growth factor (VEGF; in yellow). The VEGF draws poor-quality, leakage-prone blood vessels (in red), branching from a nearby blood supply. (Image: Jean-Sebastien Joyal)

New insights could potentially change the treatment of two diseases causing blindness: “Wet” age-related macular degeneration (AMD), the leading cause of severe vision loss in Americans over 60, and a less common condition called macular telangiectasia (MacTel) that occurs in middle age.

Both diseases are caused by abnormal growth of misshapen, leaky blood vessels in the eye that damages the macula, the central part of the retina needed to for straight-ahead vision.

The trigger for this pathologic process had been widely thought to be oxygen deprivation. However, findings published today by Nature Medicine suggest another cause: dysfunctional energy metabolism in the eye that starves the retina’s photoreceptors of fuel.

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Blocking bad vessels: A new target for retinopathy, macular degeneration

blood vessels retinopathy

The development of blood vessels is a part of normal growth in almost all tissues. But it can also be pathological: Many eye conditions leading to blindness involve abnormal blood vessel formation, including retinopathy of prematurity in infants, diabetic retinopathy and wet, age-related macular degeneration (AMD).

Blood vessels produced under stress conditions such as inflammation or low oxygen, especially in the retina, are apt to be poorly constructed and leaky. Vascular endothelial growth factor, or VEGF, has been shown to contribute to pathologic vessel growth, and anti-VEGF treatments are now widely used to control the overproliferation of blood vessels, such as Lucentis for wet macular degeneration.

Unfortunately, VEGF-binding antibodies can block not just excess VEGF but the baseline normal amount needed for vessels and neighboring neurons to survive, with potentially serious side effects.

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