Dec 21 2020
Researchers from the University College London (UCL), in association with the Western Eye Hospital in London, have developed a first-of-its-kind eye test that may predict wet age-related macular degeneration (AMD)—the most common cause of severe sight loss—three years before the development of symptoms.
DARC image (above) and corresponding OCT image slice (below). Image Credit: Novai/UCL Institute of Ophthalmology/Western Eye Hospital.
The investigators believe that the new test could enable the early detection of the disease so that treatment can successfully prevent any loss of vision.
The study results were recently published in the Expert Review of Molecular Diagnostics. The research work was financially supported by Wellcome.
Wet AMD, also called macular disease, is the leading cause of severe and permanent sight loss in the United Kingdom.
The diagnosis of wet AMD currently depends on individuals developing symptoms, which subsequently makes them seek advice from a clinician. At first, individuals with wet AMD would observe a distortion in their vision, generally interfering with their reading. But this may soon develop into complete total vision loss, which may prove rather difficult to elderly patients who fear blindness and the resultant loss of independence.
Wet AMD is characterized by unusual growth of blood vessels, which discharge the fluid into the retina. The advent of novel treatments has resulted in relatively better outcomes for patients, for a disease that was considered incurable for more than two decades. But patient outcomes could be even better if treatment was initiated in the very first stages of the disease.
The test, known as Detection of Apoptosing Retinal Cells, or DARC for short, involves administrating a fluorescent dye into the bloodstream (through the arm). This fluorescent dye binds to retinal cells and lights up those that are going through stress, or in the process of apoptosis, a kind of programmed cell death.
The injured cells emerge as bright white when observed during eye examinations—the DARC count will be higher if cells are considerably damaged.
One difficulty with assessing eye diseases is that specialists usually do not agree when observing the same scans, and hence, the team has integrated an AI algorithm into their technique.
With the help of the same technology (test), the team had earlier found that they can spot the earliest signs of the progression of glaucoma. This latest project, which represents part of the same ongoing clinical trial of DARC, evaluated 19 study participants, who had earlier displayed signs of AMD, but not essentially in both eyes.
The AI algorithm was recently trained to spot the formation of new and leaking blood vessels, which matched with the spots picked up by DARC.
The new study noted that DARC can especially highlight endothelial cells (which line the human blood vessels) under stress in the retina. Such stressed cells subsequently estimate future wet AMD activity with the development of new and leaking blood vessels observed in patients three years later, with the help of traditional eye scans with Optical Coherence Tomography (OCT).
According to the researchers, their new test could prove useful in detecting new lesions in a person afflicted by AMD, usually in the opposite, unaffected eye, and might ultimately be beneficial for screening people over a certain age or with familiar risk factors.
Francesca Cordeiro, Study Lead Researcher, Institute of Ophthalmology, University College London
“Our new test was able to predict new wet AMD lesions up to 36 months in advance of them occurring and that is huge—it means that DARC activity can guide a clinician into treating more intensively those patients who are at high risk of new lesions of wet AMD and also be used as a screening tool,” added Cordeiro, who is also affiliated to the Western Eye Hospital Imperial College Healthcare NHS Trust.
The researchers hope to continue their work with a clinical trial with more participants and also hope to examine the test in other eye diseases as well.
Our Time to Focus report on the social and economic impact of sight loss stressed the importance of early detection for prevention of sight loss, and so this is a very encouraging development in tackling the leading cause of blindness.
Sherine Krause, Chief Executive, Fight for Sight
DARC is being commercialized by Novai, a recently established company for which Professor Cordeiro is the Chief Scientific Officer.
Source: https://www.ucl.ac.uk/