July 20, 2015
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Pyron Award lecture focuses on optogenetics as vision restoration strategy

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VIENNA — The Pyron Award lecture at the American Society of Retina Specialists meeting focused on optogenetics, an exciting advancement with the possibility of restoring vision in blind patients with inherited retinal degeneration.

Gary W. Abrams, MD, explained that the concept, first described in 2005 by Boyden and colleagues, consists of the introduction of the genetic material of a light-sensitive protein into the cell membrane of light-insensitive retinal cells to effectively turn them into photoreceptors.

Gary W. Abrams

Studies are currently ongoing with channelrhodopsin-2 (ChR2), a microbial rhodopsin isolated from green algae.

“In green algae, this light-sensitive protein is responsible for phototaxis, the ability to move toward light to accomplish photosynthesis,” Abrams said.

Attached to a viral vector, ChR2 incorporates into ganglion cells, sensitizing them to blue light.

“The neuron turns into a photoreceptor and can send a signal toward the brain that is interpreted as a visual signal,” he said.

Animal experiments have shown evidence of light response, and research is ongoing to overcome current limitations of the technique.

“Currently there are still barriers to success, but they are all likely manageable barriers,” Abrams said.

Several engineered variants of ChR2 have been produced to improve kinetics and light sensitivity and to shift spectral sensitivities toward the red range, which is more consistent with daylight and safer at high light intensities. Methods to enhance transduction into the human retina are also under investigation, Abrams explained.

The first human trials might start as early as the end of this year. – by Michela Cimberle

Disclosure: Abrams reports no relevant financial disclosures.