The new artificial retina is 5 times better than the existing ones
Researchers at the Stanford University School of Medicine, working under the guidance of Professor Daniel Palanker, have developed a wireless retina implant that in the future will restore vision five times better than existing devices. The results of studies on rats indicate the ability of the new device to provide functional vision to patients with degenerative diseases of the retina, such as retinal pigmented dystrophy and macular degeneration.
Degenerative diseases of the retina lead to the destruction of photoreceptors – the so–called rods and cones - while the rest of the eye, as a rule, remain in good condition. The new implant uses the electrical excitability of one of the populations of retinal neurons known as bipolar cells. These cells process the signals coming from photoreceptors before they reach the ganglion cells that send visual information to the brain. By stimulating bipolar cells, the implant uses important natural properties of the neural system of the retina, which provides more detailed images compared to devices that do not affect these cells.
The implant made of silicon oxide consists of hexagonal photovoltaic pixels that convert the light radiation emitted by special glasses put on the patient's eyes into an electric current. These electrical impulses stimulate the bipolar cells of the retina, triggering a neural cascade reaching the brain.
Existing retinal prostheses are powered by devices placed outside the eye and connected by wires to a set of retinal electrodes. Implantation of such devices requires complex surgical intervention, and the achieved visual acuity is approximately 20/1200.
The Snellen table adopted in English-speaking countries ends at 20/200. At the same time, the patient from a distance of 6 feet understands only the letter in the top line. A value greater than 20/1000 is considered almost complete blindness.
The new photovoltaic implant benefits significantly due to its small size, modular design and absence of wires, which makes it possible to use minimally invasive surgical interventions. Visual tests on rats have demonstrated his ability to achieve visual acuity equivalent to 20/250 (indicators from 20/200 to 20/400 are considered a serious visual impairment, but this is still better than almost complete blindness).
The developers, together with the French company Pixium Vision, plan to conduct the first clinical trial of the new implant next year, which will involve patients who have lost their eyesight due to a genetic disease of retinal pigmented dystrophy.
They also plan to achieve higher visual acuity by developing chips with smaller pixels. To ensure that nerve signals reach the target neurons, they plan to equip each of the electrodes with a tiny prong that will be embedded in the layer of target cells. The ultimate goal is to create a device that provides vision restoration to the level of 20/120 (0.17 according to the LogMAR system used in the CIS countries).
Article by Henri Lorach et al. Photovoltaic restoration of sight with high visual acuity is published in the journal Nature Medicine.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on materials from Stanford University School of Medicine:
Photovoltaic retinal implant could restore functional sight, researchers say.
28.04.2015