Retinal implant partially restores sight in blinds

London: Blind people were able to read signs, tell the time and distinguish white wine from red after surgeons fitted them with retinal implants to partially restore their vision.

Five of the first eight patients enrolled in a clinical trial of the retinal implants found the electronic chips improved their eyesight enough to be useful in everyday life, the Guardian reported.

All those involved - men and women aged 35 to 62 - had lost their sight to retinitis pigmentosa, a hereditary disease that destroys the light-sensitive cells in the eye, the researchers wrote W in Proceedings of the Royal Society B.

The chip stands in for the defunct cells by detecting light rays and converting them into electrical pulses, which are sent along the optic nerve to the brain.

Each patient spent up to 10 hours in surgery to have the 3mm by 3mm chip implanted in one eye. The chip is studded with 1,500 light-sensitive elements that pick up light falling on the macula, the most light-sensitive part of the retina.

The chip does not restore vision fully. Instead, patients see light and dark patches in a small part of their visual field, as if they had black-and-white tunnel vision.

For example, one patient made out a white goose swimming on water and another saw a sunflower stem.

Three patients could immediately read letters, such as T, V, L and O. In another test, five participants could track bright dots as they moved across a computer screen, according to the team led by Eberhart Zrenner at the University Eye Hospital in Tubingen, Germany.

The chip is powered wirelessly from a battery the patient wears in their pocket, so none of the equipment is clearly visible. A dial worn behind the ear allows the patient to adjust the brightness for different lighting conditions.

"We`ve had success with the implants so far, there is no doubt about that. We`ve had completely blind patients who were able to see things again, but the technology is still early, we need to develop it further," said Robert MacLaren, a consultant retinal surgeon involved in the trial at Oxford Eye Hospital.