Gene Therapy May Restore Vision

Congenital blindness aided by gene therapy in patients other eye

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(RxWiki News) Gene therapy was previously shown to aid patients with congenital blindness in one eye. A small trial has found success in treating the second eye, restoring vision in dim-light settings.

The three adult patients treated during the trial had already been treated with gene therapy in their other eye, and after the second therapy are able to navigate obstacles in low-light situations.

"Get regular eye exams so declining vision can be identified early."

Dr. Jean Bennett, Kirby professor of Ophthalmology at Perelman School of Medicine at the University of Pennsylvania and co-leader of the study, said that patients had reported the gene therapy procedure was life-changing.

"They are able to walk around at night, go shopping for groceries and recognize people's faces—all things they couldn't do before. At the same time, we were able to objectively measure improvements in light sensitivity, side vision and other visual functions," Dr. Bennett said.

During the same study, researchers had previously treated 12 patients with Leber congenital amaurosis (LCA), a retinal disease that progresses to total blindness by adulthood, with gene therapy. Four of the patients were children under the age of 11. Previously only the eye with the worse vision was treated, with six of the participants showing enough improvement that they were no longer classified as legally blind.

Following animal trials that indicated treating the second eye would be safe and effective, investigators injected vector containing a corrective gene into the untreated eyes of three patients. Those patients had their other eye treated one to three years earlier.

Though there had been concerns that re-administering the treatment could prompt an inflammatory response that would lower the expected benefit in treating the second eye, no adverse reactions were reported.

The patients were followed for six months and had significant improvement to light sensitivity. Two of the patients were able to successfully navigate an obstacle course in dim light.

In addition, participants underwent functional magnetic resonance imaging (fMRI), which revealed an unexpected benefit of improved brain responses to the eye's sensitivity in dim light. Both eyes showed improvement and researchers suspect that may be because the eyes were better able to coordinate with each other when fixating on objects.

Additional studies are needed before gene therapy for retinal disease will be offered to the public. The therapy also is a promising for other retinal eye diseases, Dr. Bennett noted.

"This is very exciting research using a novel approach to replacing damaged genes in the eye," noted Dr. Christopher Quinn, an optometrist with Omni Eye Associates. "The fact that patients noticed subjective improvement in their vision along with objective evidence of brain stimulation with fMRI provides hope for many who suffer from degenerative genetic eye diseases."

The study was recently published in Science Translational Medicine.

Last Updated:
February 14, 2012