News Release

Age-related macular degeneration increasing due to aging populations

Control of risk factors such as smoking and diet, the use of targeted drugs, and new treatments must be embraced

Peer-Reviewed Publication

The Lancet_DELETED

As populations age, the prevalence of age-related macular degeneration (AMD), which can cause progressive blindness, can only increase. Approximately 20% of people aged 60 years and older in some countries may have the early stages of this disease. While a decade ago, treatment was largely unavailable, the advent of targeted drugs such as vascular endothelial growth factor (VEGF) suppressants has transformed management of the condition. The issues around AMD are discussed in the first paper in The Lancet Series on ophthalmology, written by Professor Tien Yin Wong, Singapore Eye Research Institute, National University of Singapore, Singapore, and colleagues.

AMD is a progressive chronic disease of the central retina and a leading cause of vision loss worldwide. The early stages of the condition are usually asymptomatic, but patients then begin to accumulate white/yellow spots of material called drusen, visible on examination of the retina. Most visual loss occurs in the late stages due to one of two processes, commonly called 'wet' and 'late dry'. In the wet form, sudden leakage of blood and fluids in the central retina may lead to a rapid drop in vision and subsequent permanent visual loss due to scarring. In the late dry type, there is progressive visual loss due to a slow degeneration and decline in retinal function.

The development of two drugs, Lucentis (ranibizumab) and Avastin (bevacizumab), have transformed care for wet AMD. They are targeted therapies suppressing VEGF, and data suggest they can prevent severe vision loss in 95% of patients, and significantly improve vision in 40%. Lucentis is considerably more expensive (US$1593 per injection) than Avastin ($42), but it has been given approval for treating AMD, whereas Avastin has not as yet been given approval, but is widely used on an off-label basis. This has led to legal action in the UK by Novartis, the manufacturer of Lucentis, to prevent UK National Health Service Trusts from using Avastin for this purpose. The paper also raises the issue of safety, since both treatments require monthly injections and long-term safety data are not yet available. Continuous suppression of VEGF might increase the risk of vascular events. The authors say more data are needed on this.

Environmental and lifestyle factors have a major part to play in AMD. While older age is a risk factor that is non-modifiable (i.e. nothing can be done about it); smoking has consistently been shown to increase risk of developing the condition, as has obesity and failure to have adequate antioxidants in the diet such as vitamin A, C, E, and zinc. Having a darker iris, previous cataract surgery, or being long-sighted also increase the risk.

Another major discovery is that AMD has a strong genetic association. These include genes connected with the immune system, HDL (good) cholesterol, and also those related to mechanisms involving collagen, the eye's extra-cellular matrix, and angiogenesis (the growth of new blood vessels).

Besides Lucentis and Avastin, new VEGF suppressant drugs are currently in development, and research is exploring possible roles for anti-inflammatory drugs, genetic approaches, stem-cell therapy, and retinal prostheses.

The authors conclude: "Age-related macular degeneration is a major cause of visual impairment in older adults. No effective preventive drug therapies exist although nutritional and behavioural modifications can reduce progression to advanced age-related macular degeneration...anti-VEGF therapies have proven to be effective in reducing and, in some cases, reversing visual loss in those with AMD, although the monthly or bi-monthly treatment burden is high and the systemic long-term safety of these drugs remains unclear. A host of novel treatment modalities, including inhibition of other angiogenic factors, new preventive approaches, regenerative therapy, and visual prostheses, are on the horizon. These hold the promise of even better outcomes in the near future."

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Professor Tien Yin Wong, Singapore Eye Research Institute, National University of Singapore, Singapore. T) +65 98565354 E) ophwty@nus.edu.sg


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