EVERY DAY, Dr S. Natarajan, chairman of the Aditya Jyot Eye Hospital in suburban Mumbai, receives at least five patients who live in darkness.

One-sixth of the world’s blindness cases occur in India but futuristic medical technology may not help every case. “At present there is nothing we can do for a patient whose retina does not work,” said Natarajan.

But there remains one ray of hope for some patients of permanent retinal damage, a condition that can be neither cured nor reversed. Since over a decade, scientists in the US, Europe and Japan have been trying to perfect a tiny artificial retina implant that could bring vision back to select patients with healthy optic nerves.

Experts are designing a silicon chip — with electrodes much smaller than a pinhead — that can be implanted on the sur face of a retina or behind it. The chip could be powered by a nanobattery smaller than a hair’s breadth or by a bioprocess that would convert surrounding glucose and body fluids into an electrical signal. But worldwide, the design remains in the realm of research.

N ow the Indian Institute of Technology- Bombay (IIT-B) too has taken up the goal. “Nearly a 100 years after neurological work, we still do not fully understand how the retina works,” said Uday Sheorey, IIT-B adjunct professor in biosciences and bioengineering.

Recently, Natarajan convinced R. Chidambaram, scientific advisor to the Prime Minister, that the idea deserves central funds spread across a national team. So IIT experts in nanoelectronics and scientists at the National Brain Research Centre in Gurgaon have joined Natarajan’s doctors. Also on board will be dogs and guinea pigs from the Bombay Veterinary College , because their eyes in a petridish, are suitable for experiments on human vision. “We will do some basic studies first on the retina’s functioning and also the genetic origins of progressive retinal damage,” said Sheorey.

The retina is a thin layer of cells behind the eyeballs that senses light, and signals impulses that travel to the brain through the optic nerve. The team will surgically remove retinal tissue from donor animals and keep it alive in the laboratory. Then they will try to stimulate the retinal tissue’s photoreceptors (see graphic) electrically with a millisecond charge under a microscope, so the layers evoke signals or optical patterns that will be further studied.

“Eventually, we will study how to power an implant, conduct animal trials, and finally, human trials,” said Sheorey. The research will gradually also shift this year to the IIT nanoelectronics centre that is under construction.

Natarajan, who heads the scientific committee of the All India Ophthalmological Society, cautioned that the implant would not help all patients — for instance, if they have damaged optic nerves.

But he is relieved the Rs 7 crore phase-1 study has begun. “I have been trying to get this project started since five years,” he said. And the doctor is looking at a research timeline five to seven years ahead.

A light switch for the eye

The retina, a thin layer of cells behind the eyeballs, senses light Image of an object falls on the retina Photoreceptors behind the retinal layer convert the light colour and intensity into signals A pattern of signals travels through the optic nerve to the back of the brain where it is understood as a scene Scientists want to make an artificial retina implant for select patients with retinal degenerative diseases It will be a silicon chip implanted on the surface of a retina or behind it.