I Can See Again
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I can see again

I can tolerate reading glasses. What I�m afraid of is developing a degenerative eye disease, like many older Americans, and eventually losing my sight.

No kidding, yet it�s a reality for many seniors. Degenerative eye diseases that lead to blindness are caused by the death of photoreceptor cells, which are nerve cells in the retina that allow us to see.

For years scientists have experimented with ways to repair or replace these cells and finally, in a recent, landmark study, researchers transplanted immature photoreceptor cells in mice and restored their vision.

They first engineered mice with rods that didn�t work. Rods and cones are the two types of photoreceptor nerve cells. The cells convert light energy into signals that travel the optic nerve to the brain. Cones detect color and detail, while rods pick up black and white, peripheral, and low-light vision.

In these mice with non-working rods, researchers injected their retinas with immature rod receptor cells from young healthy mice. Within four to six weeks, one in six of these transplanted rod precursor cells were close to functioning normally. They formed nerve connections and generated signals that were transmitted to the brain for visual processing.

This is the first time transplanted photoreceptor cells have been shown to integrate into the circuitry of the retina and improve vision.

To test their results, researchers placed treated mice and diseased mice into a dimly-lit water maze. The treated mice with new rods could see well enough in low light to find a platform and climb out. The diseased mice took much longer, proving the implants work.

Researchers say the study�s success was due to the large number of photoreceptor cells they implanted. A clinical trial is already underway.


For more information…

Blind Mice Sight Restored By Transplanting Light-sensitive Photoreceptors
An article highlighting the important discovery that sight could be restored by transplanting light sensitive photoreceptors.

Photoreceptor Death in Mouse Models Of Retinitis Pigmentosa
An article about the death of photoreceptor cells in a mouse model of retinitis pigmentosa.

How Your Eyes Work
To learn the basics of how the eye works, go to thiis American Optometric Association web site which includes links to information on how to take care of your vision. The University of Michigan also has a good site for more information about the eye here.

See All You Can See
The National Eye Institute offers this wonderful interactive web page to teach kids about the eye and vision.

Stargardt Disease
Here you can learn about Stargardt disease, the most common form of inherited juvenile macular degeneration. Inherited as an autosomal recessive trait, it is a severe form of MD that begins in late childhood and leads to legal blindness. Stargardt disease is symptomatically similar to age-related macular degeneration, and it affects approximately one in 10,000 children.

Saffron Supplementation in Stargardt's Disease
The US National Institute of Health has a great deal of information about the many clinical trials ongoing in the US. Information about one trial for treating Stargardt disease is available here.