Professor Paulo Stanga
The leading cause of blindness in the developed world, incidence of age-related macular degeneration (AMD) is increasing with growth of the elderly population. Manifesting in both dry (atrophic) and wet (neovascular or exudative) forms, dry AMD accounts for 80-90% of cases. In the United States, approximately 15 million people have AMD, in Europe about 20 million people have a form of the disease. In the United Kingdom alone, the Macular Society estimates that more than 44,000 people develop dry AMD each year. Current treatments for dry AMD are limited, but a sophisticated bionic eye is currently in trials offering potential hope for many sufferers.
Characterised by progressive deterioration of the macula or retina‚s central region, AMD causes loss of the central visual field. Extracelllular deposits, known as drusen, form in and around the macula, inhibiting sight. Risk factors include age, smoking, environment, and family genetic history.
There are no pharmaceutical treatments for dry AMD. A telescope implant is available, but requires extensive training and is only approved for end-stage AMD. Peripheral vision is lost with the telescope implant, therefore vision in the other eye must be of higher standard. Experimental treatments include acupuncture, microelectrical stimulation, and rheopheresis. Similar to kidney dialysis, rheopheresis is a procedure where vascular risk factor substances are removed such as LDL cholesterol, fibrinogen and lipoprotein A. Clinical trial funding for dry AMD rheopheresis was halted in the United States, but continues in Canada and Germany.
However, a feasibility trial is ongoing with electronic retinal implants, or a bionic eye system, for dry AMD. Originally developed to treat retinitis pigmentosa (RP), the device is being explored for dry AMD. Profiled in a previous Medtronic Eureka article (https://europe.medtronic.com/xd-en/transforming-healthcare/EUreka/innovation-articles/bionic-retinal-implants.html) on RP treatment, the implant system converts video images from a miniature video camera worn on glasses into electrical pulses. These are wirelessly transmitted to an electrode array on a tiny microchip with 1,500 miniature electronic photodiodes, which is attached to the retina. These microelectrodes stimulate the retinal layers in response to incident light and send information to the brain via an inductive coil implanted beneath the skin behind the ear. Unlike the miniature telescope implant, dry AMD patients retain their peripheral vision, in addition to having their central vision enhanced.
WE ARE VERY EXCITED BY THIS TRIAL AND HOPE THAT THIS TECHNOLOGY MIGHT HELP PEOPLE, INCLUDING CHILDREN WITH OTHER FORMS OF SIGHT LOSS.Professor Paulo Stanga
Research is being conducted at Manchester Royal Eye Hospital in the United Kingdom, led by Professor Paulo Stanga. Initially the plan is to implant the bionic eye into five dry AMD patients. Stanga, an ophthalmologist and vitreo-retinal surgeon at the hospital and professor of ophthalmology and retinal regeneration at the University of Manchester, reported to the BBC after the first successful implant that he was optimistic. The device was switched on two-weeks post-implantation with the Principal Investigator describing the patient‚s progress as “truly remarkable; he is seeing the outline of people and objects very effectively.” Stanga hopes that with training patient‚s device provided central vision will integrate with their own peripheral vision, but he cautions that it is early on in the research. Prospective patients should be aware that the procedure is complex requiring a four-hour surgery and exhaustive post-operative training. As with the telescope, bionic eye implant patients must be willing to commit to extensive training to achieve maximum effectiveness. The implant cannot provide extremely detailed vision, but patients should be able to distinguish door frames and large objects, improving over time as settings are adjusted and the patients train on the device.
The five patients in the advanced dry AMD feasibility study will be provide data on the safety and effectiveness of the bionic eye system. If positive results continue, a larger scale clinical trial will launch with the goal of market approval in the future. While it holds exciting promise, cost may prove to be a hurdle. Each system is expected to be priced at 150,000. In addition, implant longevity remains an unknown, especially as it must function in a wet environment - always a challenge for electronic devices. Yet, for millions of dry AMD patients, the bionic eye offers a ray of hope in an otherwise desolate treatment field. Professor Stanga also believes that the bionic eye may prove useful for a variety of other vision loss diseases and could be suitable for children. “We are very excited by this trial and hope that this technology might help people, including children with other forms of sight loss”, he said.