Researchers theorized that if they could “upgrade” these photoreceptor cells with the non-defective gene then damage to the photoreceptor cells would cease and any remaining healthy cells would regain their ability to function. A virus was used to inject the functioning gene into the target cells and within a week vision improved and remained so after 90 days — the study’s endpoint.

In theory, the younger the patient, the better this therapy will work because the degenerative nature of the disease will have had less time to cause permanent destruction to photoreceptor cells. Trials are now underway with younger patients and the researchers are hopeful that these younger patients will see substantial, perhaps even full recovery of vision.