Age-related macular degeneration (AMD) is the leading cause of severe visual loss in Europe and North America and, with an ageing population, the burden of this disease is projected to increase dramatically.
As its name suggests AMD predominantly affects the macula, the centre of the retina that is important for reading and detailed vision. It can be classified into early and late stages based on specific clinical features. Early AMD is characterised by the presence of drusen (tiny yellowish deposits under the retina) and is compatible with reasonable vision. However, many patients with early AMD progress to the vision-threatening late forms of AMD.
The late ‘wet’ or neovascular form is characterised by the growth and leaking of abnormal blood vessels beneath the macula causing severe loss of vision.
Currently, we have treatments for late neovascular AMD but these involve intensive intervention with frequent injections into the eye and long-term monthly follow-up of the patient. Such treatments can be problematic to deliver, and only a third of patients recover some of their lost vision. We have no effective treatments for early AMD or for the late dry atrophic form of AMD.
Our objectives are:
- to establish further genetic risk factors for AMD and to determine the impact of high versus low risk genotype on rate of progression of disease and response to therapy,
- to assess the early changes in AMD and the features of the atrophic variant of the disease. Current investigations offer the best hope for early diagnosis, exploring various therapeutic options which should be available in the next 3-5 years.
- to develop surgical treatments for AMD. These will benefit patients directly and be widely available within the next five years. Further advances could follow with the use of stem cell replacement in the next 5-10 years. The aim is for lasting, safe restoration of function in AMD and in conditons involving outer retinal degeneration.
The London Project to Cure Blindness (AMD)
One of our approaches to treating AMD is being explored through the ground-breaking research of the London Project to Cure Blindness, which is led by Professor Pete Coffey at the UCL Institute of Ophthalmology. Pete and his team aim to replace the retinal pigment epithelium (RPE) cells at the back of the eye that are affected in AMD, with human embryonic stem cells (HES) that have been transformed into RPE cells. The idea is to transplant these RPE cells into the patient on a specially engineered patch that will be inserted behind the retina.
Another important arm of the project is to develop the technology by which HES cells can be transformed into photoreceptors (light detecting cells) and then transplanted into patients. It is believed that the photoreceptors are lost after the RPE has degenerated.
A novel intervention to treat geographic atrophy (late ‘dry’ AMD)
There is currently no effective therapy to prevent progressive vision loss in patients with atrophic AMD. In 2011, we commenced a pioneering clinical trial of a novel intervention that prevents the build-up of a key waste product that damages the cells under the retina. As a precursor to this trial, the study team at Moorfields and the UCL Institute of Ophthalmology are developing new ways of assessing atrophy disease progression, and functional changes in patients with this disorder to allow for more effective clinical trial design.
The ABC trial for wet AMD
Current strategies for the use of drugs to treat neovascular AMD lead to gradual drop-off in vision, which means that the benefits of these intensive treatments are being lost over time. Moorfields was the lead and coordinating centre for an important randomised multi-centre trial of an anti-VEGF drug (a substance that prevents the formation or growth of new blood vessels). This trial not only showed that the anti-VEGF drug resulted, on average, in the recovery of lost vision, but it also led to the development of an individualised apprach to treatment that prolonged this improvement in vision and so reduced the treatment burden compared to current interventions.