© Nguyen Huy Kham / Reuters
Treatment for one of the leading causes of blindness could be available within five years. That's according to scientists who used a revolutionary stem cell therapy to restore vision in two patients.

The patients - a woman in her 60s and a man in his 80s - suffered from severe visual impairment caused by age-related macular degeneration (AMD). The disease causes the gradual loss of sight due to blurring or loss of central vision.

AMD is the most common cause of blindness in people over the age of 50, causing the gradual loss of sight due to blurring or loss of central vision. It takes two forms: wet and dry. The patients treated in the trial had the rapidly developing wet AMD and could not read at all, even with spectacles.

Scientists from the London Project to Cure Blindness examined whether the diseased cells at the back the patients' affected eye could be replenished using a stem cell-based patch. A specially engineered surgical tool was used to insert the patch under the retina in an operation lasting up to two hours.

It's the first time a completely engineered tissue has been successfully used in this way, according to the project. Following the trial, the patients were monitored for a year and reported significant improvements. The pair went from being unable to read even while wearing glasses, to reading 60-80 words per minute with normal reading glasses.

"After the surgery my eyesight improved to the point where I can now read the newspaper and help my wife out with the gardening. It's brilliant what the team have done and I feel so lucky to have been given my sight back," trial participant Douglas Waters, 86, said.

The team hopes the technique will also help treat dry AMD in the future."We hope this will lead to an affordable 'off-the-shelf' therapy that could be made available to NHS patients within the next five years," Professor Pete Coffey, of the UCL Institute of Ophthalmology, said.

An estimated 1.8 million Americans aged 40 years and older are affected by AMD, according to the Centers for Disease Control and Prevention (CDC). The number suffering the disease is estimated to reach 2.95 million in 2020.

The London Project to Cure Blindness is a partnership between Moorfields Eye Hospital NHS Foundation Trust, the UCL Institute of Ophthalmology, and the National Institute for Health Research (NIHR). Details of the clinical study are published in Nature Biotechnology.