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Electrical impulses that help you ‘see’

delhi Updated: Jan 28, 2010 22:50 IST
Ayesha Banerjee
Ayesha Banerjee
Hindustan Times
Highlight Story

For patients blinded by Retinitis Pigmentosa (RP), a type of progressive retinal dystrophy, Dr Rajat Agrawal, a US-based Indian surgeon, is a messenger of hope.

He is working on a device to help them ‘see’ again.

Vitreo-retinal surgeon Dr Agrawal, currently the director of Center for Retinal Degenerative Diseases at the Doheny Eye Institute, University of Southern California, is using electrical impulses to stimulate the retina — the light-sensitive membrane at the back of the eye that sends images to the brain — to help it “receive visual information”.

The device has FDA clearance after extensive trials and is currently being perfected for use.

“The work precedes me by almost a decade,” said Dr Agrawal.

“It began after it was demonstrated that the retina in a RP patient showed some (response), even though the main retinal cells (the rods and cones) had been completely damaged. It was thought that a safe current could help develop a visual impulse when given close to the retina, which would allow the rest of the visual system to function and the brain to perceive an image,” he said.

The new device has a coil that is placed on the outside of the patient’s eye, which is connected by a cable to a chip surgically fixed on the retina.

The patient wears spectacles fitted with a video camera, which transmits data to the device in the eye wirelessly. After trials, patients have perceived spots of light, and later shapes as per the stimulation on the retinal surface. The ‘eureka’ moment came when Dr Agrawal was sketching something on a board while discussing management of retinal detachments in patients.

“Our team had been using a band on the outside of the eye to reattach the retina. I realised that by using the same concept but fitting electronics in some portions of the band, we can make the device completely accessible to a retinal surgeon for implantation,” he said.

Dr Agrawal is working to bring the treatment to India, where, he said, it can be made cheaper with more production of more devices.

The device can be manufactured in India after getting the necessary licences.

India has a significant number of RP patients, at least four times more than the current prevalence estimate of 1 in 4,000 patients in the West.