In the UK, age-related macular degeneration, or AMD - a progressive sight loss condition is set to rise by a third, says research published in Ophthalmology.
AMD, which comprises "dry" (geographical atrophy) and "wet" (neovascular AMD) forms, accounts for over half of the total number of those registered blind and partially sighted in the UK.
AMD affects part of the retina—the macula—at the back of the eye, impairing central vision. As the name suggests, it is strongly associated with ageing.
Realistic estimates of those affected by AMD have been hard to come by, but are important in terms of quantifying the extent of future health and social care service need, and the costs of new treatments, say the authors.
They analysed AMD incidence data from 31 European ancestry populations, covering a total of more than 58,000 people to calculate prevalence rates from ages 50 to 90. These figures were then applied to UK population stats for the years 2007 to 2009 to calculate a prevalence rate.
The overall prevalence of advanced (late) AMD among those aged 50 and above was 2.4%, equivalent to just over half a million cases (513,000), 60% of which were in women.
The rate increased sharply with age, with almost one in 20 (4.8%) cases among those aged 65 and above, rising to more than one in 10 (12.2%) among those aged 80 and above.
Ageing alone will increase the prevalence to 679,000 by 2020, a rise of a third, on the basis of these figures, say the authors.
They also estimated the annual number of new AMD cases. The calculations indicated 71,000 new cases of late AMD every year, of which 40,000 will have wet AMD.
This is much higher than the figure of 26,000 new cases a year used by the NHS treatments watchdog, the National Institute for Health and Clinical Excellence (NICE), say the authors.
Photodynamic therapy and newer drugs (antivascular endothelial growth factors) are increasingly being used to treat the wet form, but there is currently no effective treatment for the dry form of AMD. And the calculations suggest that an additional 44,000 people a year will be diagnosed with this untreatable form.