Ms Tsang Wy Suet Yun, a patient at the University of Hong Kong Eye Institute who was legally blind for 15 years, can see again. Ms Yun, who suffered from retinitis pigmentosa, underwent a surgery at the institute for retinal implants in February 2012 that treated her condition. The implant, a microchip developed by German company Retina Impant, helps restore lost vision.

The implant at the human clinical trial stage is a 3mm x 3mm microchip with 1,500 electrodes that is implanted below the retina, specifically in the macular region of the eye. Since the microchip needs electrical power to operate, transmitter coils are placed under the patient's skin and post-implant, the micrchip is turned on to begin sight restoration. The electrodes on the chip absorb the light entering the eye, converting it into electrical energy to stimulate nerves within the retina. This stimulation is then relayed to the brain through the optical nerve leading to improved field of vision.

As the patient needs to develop new internal processes for interpreting the images, it takes several weeks to fully realize new sight capabilities. According to the result announced by the company, Ms Yun can see light and able to read letters projected on a screen in the laboratory.

Retina Implant, which specializes in subretinal implants, conducted the first human trial in 2005. For the trial, subretinal microchips were implanted on 11 patients with retinitis pigmentosa. Unlike the patients who received epiretinal implants, those who received subretinal implants of Retina Implant were able to see objects and shapes so clearly that they could combine letters to form words and read at a basic level. The results showed such patients were also able to recognize foreign objects and no complications reported have been reported till date.

The company is presently carrying out a second, multi-center human clinical trial in Germany, Hong Kong and the UK. The company hopes to provide implants to a total of 60 patients under the second trial. In this trial, the patients will have the option to keep the implant permanently, unlike the first trial when the implant was removed after four months.