Retinal Implant Restores Limited Sight to Blind

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Loewenstein added that he has seen no evidence to suggest that electrode technology is yet poised to replicate the retina's complexity.

"When we put those electrodes in and stimulate the retina, people can see spots of light," he explained. "But we have not yet succeeded in translating those spots of light into true images. The analogy is to a scoreboard with individual light bulbs lined up to make up a '1' or a '2' or an 'A' or a 'B'. A person with normal vision can interpret all the bulbs as a whole to construe a letter or number. And we have all hoped, naively, that we could mimic this ability with a prosthesis. But, so far, it just hasn't worked out that way."

Jim Weiland , a member of Humayun's research team and an associate professor of ophthalmology, agreed there are many obstacles on the path toward full sight restoration. But he remains optimistic.

"Yes, it's true that how we stimulate the retina to convey useful information is still an open question," Weiland acknowledged. "So, this device is not something that's going to replace the natural vision that you and I have. But I do expect that there will be some benefit that a completely blind person may derive from this device, in terms of providing some ability to make out imagery and navigate about."

"Of course, this benefit has to be proven in a trial," added Weiland. "We think we're on the right road. But we still have a lot of work to do."

More information

For more on retinitis pigmentosa, head to the Foundation Fighting Blindness.