Scientists have developed a new method to predict which patients with age-related macular degeneration are likely to suffer from the most debilitating form of the disease.
The new method, by Stanford University School of Medicine scientists, predicts, on a personalised basis, which patients' AMD would, if untreated, probably make them blind, and roughly when this would occur.
Simply by crunching imaging data that is already commonly collected in eye doctors' offices, ophthalmologists could make smarter decisions about when to schedule an individual patient's next office visit in order to optimise the chances of detecting AMD progression before it causes blindness, researchers said.
AMD is the leading cause of blindness and central vision loss among adults older than 65. In the disease, macula - the key area of the retina responsible for vision - shows signs of degeneration.
During normal ageing, yellowish deposits called drusen form in the retina, which is the light-sensitive layer of tissue at the back of the eye. As drusen increase in size and number, they eventually begin to damage the light-sensitive cells of the macula.
This stage of the disease, called "dry" AMD, can mean blurry central vision and impaired day-to-day activity.
While about four of every five people with AMD have the dry form of the disease, it's the so-called "wet" form that most concerns ophthalmologists, because it accounts for 80-90 per cent of all legal blindness associated with the disease.
In wet AMD, abnormal blood vessels accumulate underneath the macula and leak blood and fluid. When that happens, irreversible damage to the macula can quickly ensue if not treated quickly.
But until now, there has been no effective way to tell which individuals with AMD are likely to progress to the wet stage.
Current treatments are costly and invasive - they typically involve injections of medicines directly into the eyeball.
In the new study published in the journal Investigative Ophthalmology & Visual Science, the researchers derived a formula which they said predicts, with high accuracy, whether a patient with mild or intermediate AMD will progress to the wet stage.
The formula distinguishes likely from unlikely progressors by analysing patient data that's routinely collected by ophthalmologists and optometrists when they perform retinal scans with an imaging technique called spectral domain optical coherence tomography.
The resulting stream of data is computationally converted into an extremely high-resolution, three-dimensional image.
From this computerised analysis, the investigators are able to generate a risk score: a number that predicts a patient's likelihood of progressing to the wet stage within one year, three years or five years.
