Researchers based at the Department of R&D, NIHR BRC for Ophthalmology, Moorfields and UCL Institute of Ophthalmology, London, have reported that the leading cause of certified vision impairment in England and Wales continues to be age-related macular degeneration (AMD). Analysis and review of certificates of vision impairment records showed that for the period from April 2012 to March 2013, degeneration of the macula and AMD were listed as the main cause in 50% of severe sight impairments (SSI; blindness) and 52.7% of sight impairment (SI; partial sight). Glaucoma was cited as the second most common cause with 11% SSI and 7.6% SI while genetic disorders overtook diabetes as the third leading cause of SSI. The statistics are likely to fuel continuing basic and clinical research efforts globally, especially in efforts to improve drug delivery techniques aimed at reducing the number of injections required for various anti-VEGF treatments.
The research takes advantage of UK records on blindness dating back to 1851 allowing epidemiologists to accurately track the incidence of vision loss and, more recently, the causes for both low, partial and complete vision impairment. The researchers documented 24,009 certificates of vision loss of which 10,410 were patients certified with severe sight impairment. AMD, neovascular, atrophic and mixed, was the leading cause of SSI at 50% however, the figure had actually decreased from what was recorded in the 2007–2008 period where the figure for AMD was 58.6%. After AMD, the second most common cause of blindness, glaucoma, showed an increase to 11% on the corresponding figure of 8.4% in 2007–2008. Certifications citing genetic disorders as the third leading cause of SSI rose from 5.5% in 2007–2008 to 8.2% in 2012–2013. The apparent increase of genetic disorders resulted in diabetes being pushed into fourth position, listed as being responsible for 5.4% of SSI in 2013 compared to 6.3% in 2007–2008. Following on from diabetes the researchers listed optic atrophy (4.9%), cerebrovascular disease (2.7%), disorders of visual cortex (2.6%), congenital anomalies (2.1%), and retinal vascular occlusions (2%) as the next most commonly occurring entries reported on certificates of vision loss. In short, the researchers stated that “AMD, glaucoma, hereditary retinal disorders, diabetic eye disease, optic atrophy and cerebrovascular disease accounted for 82.2% of SSI certifications and the most frequently occurring causes of SI certifications (81.7%) were AMD, glaucoma, cerebrovascular disease, diabetic eye disease, hereditary retinal disorders, and disorders of visual cortex, where there was a single cause.”
The decrease in AMD figures over the 5-year reporting period (2007-2008 versus 2012-2013) is likely due to the widespread availability of effective anti-VEGF medications, in addition to the improved clinical management of the disease. The approval of such medications in certain diabetic retinopathy indications is similarly reflected in the decrease in the figures for diabetes. Obviously as the proportions of AMD and diabetes as a cause for SSI fall on the certificate of vision impairment, the relative proportional increase in genetic and cerebrovascular causes should be interpreted with caution.