Curing the Blind

My last entry discussed the use of brain activity to predict words a person hears, and how that technology may one day be used to predict a person's imagined words. I recently found an article that I found to be both intriguing and also on the topic of improving life for those with handicapped senses.

Gene therapy has been recently used to restore vision for three women who were virtually blind. The women can now avoid obstacles, read large printed words, and recognize people by their faces. Researchers predict that therapy will work even more so in children and adolescents that have the same condition that causes blindness.

The operation on these three women worked just as well as the initial operation. The initial operation took place between the years 2008 and 2011, when Jean Bennet of the University of Pennsylvania's Mahoney Institute of Neurological Sciences and her partners used gene therapy to improve the vision of a dozen adults and children who were virtually blind. These 12 patients suffered from Leber's congenital amaurosis, or LCA, which is a rare inherited eye disease that destroys photoreceptors, light sensitive cells at the back of the eye in the retina, resulting in a lack of vision.

The treatment was developed with the understanding that the disorder caused blindness through genetic mutations in retinal cells. One of the mutated genes responsible for the disorder is RPE65. RPE65 is responsible for encoding an enzyme that helps break down retinol, a derivative of vitamin A, into a substance that is needed by photoreceptors to detect light and transmit signals to the brain. Mutated forms of RPE65 prevent the production of this enzyme in the retinal pigment epithelium, an area attached to the retina responsible for breaking down retinol.

In the initial study, Jean Bennett's coauthor Albert Maguire of Penn Medicine introduced a harmless virus that carried normal copies of RPE65 into an area of the retinal pigment epithelium. He introduced the virus into one eye of each patient. The retinal pigment epithelium then began copying normal RPE65, and the study was so successful that 6 out of the 12 patients were no longer legally blind. Recently, three of the women from the initial study were given the same treatment in their untreated eye, with identical results. The women showed an improvement in vision only 2 weeks after the treatment. Not only are the women's eyes more sensitive to light, their brains were also much more responsive to optical input. To the surprise of the researchers, the second treatment also improved the vision of the eye that was initially treated. They guess that visual cortex of the second treated eye bolsters the visual cortex of the initially treated eye.

I chose this article because I am enthralled by the medical field's strides towards helping people born with preexisting conditions that limit their sensory perception. While I often like to lay out the pros and cons for various advances in medicine, I don't see any cons to the ability to cure the blind. Further advances into this field could help treat people suffering from other forms of inherited blindness and improve the quality of life for millions of people.

http://www.scientificamerican.com/article.cfm?id=gene-therapy-blindness