Considering the Path to Curing Blindness

The most prevalent causes of blindness are degenerative and associated with aging, the result of loss of cells and structure in the retina. There are numerous other causes, including optic nerve damage that can result from trauma, but these are fortunately less common. At the high level there are two main approaches that will lead to reliable future restoration of vision. The first is some form of cell therapy, inducing regeneration that would not normally take place in order to repair the damage such that the functional components of sight are restored. The second is to bypass dysfunctional tissues and replace them with machinery. At present regenerative medicine is much further ahead, while state of the art retinal prostheses consist of electrode grids that provide only a poor substitute for vision, not the real thing. Both will improve considerably in the years ahead.

Losing eyesight is a common problem, be it due to the process of aging or the development of a specific condition. A range of conditions exists where those who develop them are faced with a gradual loss of vision until their impairment is so severe that they are effectively blind. Retinal degeneration disorders have no cure. These diseases break down the retina, the layer of tissue found at the back of the eye containing cells that detect light entering the organ.

Embryonic stem cells could be used to build new retinal pigmented epithelial cells - cells that nourish retinal visual cells and absorb light - that could be transplanted into a patient. Doing this could slow or prevent the loss of the visual cells, and while deriving new visual cells from embryonic stem cells could lead to even more pronounced results, researchers have found it more difficult to successfully derive these cells and transplant them into the retina. Mouse studies have previously shown that this technique can work and that transplanted cells can integrate fully with the retina, restoring vision to the animals. Researchers have managed to derive rod cells from embryonic stem cells and are currently working on deriving cone cells and transplanting them into animals. If these trials prove successful, the next step could be human trials.

"In patients who have already lost their sight, our therapeutic goal is to restore vision. This has been successfully accomplished via the Argus II retinal prosthesis in patients with advanced retinitis pigmentosa." The 15th man in the US to receive the life-changing device is now able to make out the outlines of objects and people thanks to his new retinal prosthesis. He is now able to navigate through crowded environments - such as shopping centers - without the use of a cane. A camera connected to a pair of glasses transmits visual information to a small chip attached to the back of the eye via a small computer worn in a belt pack. The chip can send light signals directly to the optic nerve, bypassing the damaged retina and providing the patient with visual information in the form of flashes of light. While this form of vision could be considered basic compared with what normal-sighted people are used to, it is a marked improvement for many without sight. As he used his retinal prosthesis for the first time, the patient described the artificial vision as "crude, but significant."



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