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Wouldn't it be great if all we had to do was to flip a switch or press a button to turn off pain or tremors or anxiety, or even restore sight? That's the promise of a new branch of medical science known as optogenetics.

Since February of 2016 a team of doctors in Texas working for a startup in Michigan have been injecting viruses genetically engineered to carry DNA from light-sensitive algae into the eyes of 15 volunteers blinded by a condition called retinitis pigmentosa. Their hope is that these injections of DNA into the retina will reengineer cells in the eye that are ordinarily insensitive to light so that the volunteers will recover at least black and white, fuzzy, grainy vision. As this article is being written in July 2016, the first volunteer has already received her first injection and the researchers are monitoring her progress.

Using Gene Therapy to Restore Sight to the Blind, At Least in Mice

The FDA gave a license to RetroSense Therapeutics, the biotech startup in Michigan, to conduct a Phase I clinical trial (to test safety) with the Retina Foundation of the Southwest in Dallas, Texas, only in late 2015, a full 10 years after Dr. Ed Boyden, then a graduate student at Stanford University, indulged his curiosity by flashing a blue light at a nerve cell he was studying under a microscope. The nerve cell "turned off." Next Boyden and his supervising professor Dr. Karl Deisseroth discovered that shining a blue light on a mouse's right cerebral cortex would cause it to run counterclockwise. Turn the light off, and the mouse could run in straight lines.

It was another five years before Zhuo-Hua Pan of Wayne State University in Detroit showed that the same technique could be used to restore sight in blind mice, although it's a procedure that most of us would think twice about before having done on ourselves. First, the research team identified a compound in pond scum known as an opsin. They identified the gene that regulates the opsin. They use molecular engineering to create a virus that carries the opsin gene, and infect the brain of the blind mouse with the virus. The gene becomes part of the DNA of cells in the brain necessary for sight, but has to be activated by light transmitted into the brain with a tiny fiber optic cable. After this lengthy procedure, the mouse can see again.

A More Elegant Application for Restoring Sight in Humans

There have been improvements in technique so it is now possible to introduce genes into human cells without viral infection and it is possible to shine a light inside the brain without having to have a fiber optic cable dangling outside the skull. In this new method of genetically engineering cells in the human retina, the light needed to see is also the light needed to activate the newly reengineered nerves in the eye. Scientists believe that previously insensitive cells in the retina will start responding to light right away, although it may take months or years for the brain to begin to recognize and process the new information.

The treatment only changes nerve cells so that they turn on or off in the presence of light. They cannot register color. However, most of the volunteers for testing the procedure believe that having some vision, even black and white vision, is better than having no vision at all.

Continue reading after recommendations

  • National Parkinson Foundation. What's Hot in PD? Shining a Light on Parkinson’s Disease: Optogenetics Has a Bright Future in Research. August 2010.
  • Teal Burrell.Fixed by light: Flick a switch to banish pain and blindness. New Scientist. 22 June 2016.
  • Photo courtesy of centralasian:
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