This site is intended for health professionals only

Implants help blind patients see

Three patients who lost their sight after contracting a hereditary disease have seen shapes again thanks to new retinal implants.

The trio could all find a cup, a saucer and other shapes placed on a table soon after having the implant fitted.

Before that, all three were completely unable to recognise shapes - although they could sometimes sense bright light.

One of the patients could even tell the time from a clock face after having the implant fitted. He could also walk confidently and read his own name.

A British eye expert commenting on the German breakthrough said it had turned science fiction into fact.

Patients in the UK are due to receive the implant for the first time in a follow-up trial starting next year.

Two men and one woman aged 40, 44 and 38 took part in the pilot study testing the device developed by Retina Implant AG, a medical technology company based in Reutlingen, Germany.

All had the hereditary condition retinitis pigmentosa, which gradually destroys the light-sensitive retina at the back of the eye eventually leading to blindness.

After first becoming affected in early childhood, each of the patients had lost the ability to read at least five years before undergoing surgery.

The implant is fitted beneath the retina and consists of a 3mm-square array of 1,500 light sensors.

Each "photodiode" delivers a pulsed electrical signal to adjoining groups of nerve cells, sending a message to the brain.

A power supply unit is connected to the device by means of a cable passed through the skin.

Details of the trial were published in the journal Proceedings of the Royal Society B.

Copyright © Press Association 2010