Blindness

The WHO estimates about 161 million people worldwide are blind or visually impaired, and that number is expected to grow as the population ages. The most common cause of vision loss in adults over age 55 is age-related macular degeneration. It is caused by a progressive loss of cells in the back of the eye that detect light (photoreceptors) and send nerve impulses to the brain, where the signals are processed into images. There are other progressive retinal diseases leading to vision loss. They include diabetic retinopathy, in which photoreceptors are partially covered or detached by abnormal blood vessel growth, and retinitis pigmentosa, an inherited condition in which photoreceptors gradually die. To address vision loss from retinal damage, medical device makers are exploring ways to bypass the missing light-sensitive cells by implanting a microchip array that acts like a miniature video camera and sends impulses directly to the optic nerve at the back of the eye. With a retinal implant, a partial sense of vision can be restored.

Reviewed April 2, 2012
Jaimie M. Henderson, MD
Director-at-Large, International Neuromodulation Society, 2011 - 2014
Associate Professor of Neurosurgery, and, By Courtesy, of Neurology and Neurological Sciences; Robert and Ruth Halperin Faculty Scholar; Director, Stereotactic and Functional Neurosurgery; Co-Director, Neural Prosthetics Translational Laboratory; Stanford University School of Medicine, Stanford, California, USA

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