Wet age related macular degeneration (Wet AMD) is a condition where fluid from newly formed blood vessels leaks into the retina causing damage, these blood vessels form as a result of the retinal cells releasing a protein called vascular endothelial growth factor (VEGF).
Wet AMD if untreated can lead to rapid irreversible vision loss. Since 2006 effective treatment options have become available using VEGF inhibitors, which reduce the amount of VEGF in the retina and cause the new, leaky blood vessels to stop leaking and shrink. This results in a reduction of fluid in the retina and in most cases a recovery of vision.
Treatment is carried out by an Ophthalmologist at a local or regional eye department, after confirming the diagnosis of wet AMD the Specialist will carry out an intra-vitreal injection, injecting the anti-VEGF agent from the side of the eye into the vitreous humour (the jelly inside the eye) where the agent will act on the retina.
There are currently two drugs used to treat wet AMD in the UK, Lucentis® and Eylea®. When beginning treatment patients will have three injections carried out at one month intervals, once this initial ‘loading phase’ has been carried out patients will be monitored and further treatment will be carried out if required. Depending on the drug used and the severity of the initial condition, patients may be put on one of three treatment regiemes:
Pro re nata- after the initial three doses patients will be monitored every month, and if there are any signs that the wet AMD returns then further injections will be carried out.
Monitor and extend- after the initial doses, patients are called back after 6 weeks for review, should treatment not be required at this stage then the time between the reviews will be extended by a further two weeks unless further treatment is required.
Treat and extend- after the initial doses patients are given treatment at every visit. If there is no evidence of the disease returning the time between appointments will be extended by two weeks at every visit, continuing until there are signs that the disease may be returning. At which point reviews may become more frequent.
When the ophthalmologist decides to treat with Eylea® a different treatment plan is followed, following the three initial doses at one month intervals, injections are given every two months for the first year, following which patients are reviewed on a ‘treat and extend’ basis.
Reduced Vision,
For patients with reduced vision, either through AMD or other forms of retinal damage where standard spectacles cannot improve the vision a number of options are available.
Reading spectales with strong reading prescriptions may aid with smaller print, these spectacles require the patient to hold the reading material closer than normal to read, which may take time to get used to.
Hand held or stand magnifiers, such as those made by Eschenbach provide high quality, high magnification optics and are produced both with and without inbuilt bright LED illumination. These can be used in conjunction with distance or reading prescriptions.
For patients with larger areas of damage, electronic closed-circuit magnifiers such as the Monomouse may be used. These attach to your television and can be used to provide higher magnification without having to hold reading materials at an uncomfortably close distance.
DRY AMD
As we age the eye, like many parts of the body operates less efficiently. In some people this loss in efficiency shows as a build up of waste products under the retina. These waste products, called drusen, come from the normal function of the rod and cone cells in the retina.
When large amounts of these waste products build up they lower the amount of nutrients that can reach the rods and cones, which leads to the cells in the back of the eye not working as well. In some occasions the cells release a protein called vascular endothelial growth factor (VEGF) to encourage new blood vessels to grow to increase the amount of nutrients reaching the cells in the retina.
As the amount of damaged cells increases, areas of the retina can stop functioning altogether leading to loss of central vision.
In the early stages the build up of deposits can alter the shape of the retina, leading to the appearance of distortion of straight opjects such as door edges and table tops. It may also be noticed as a difficulty reading, where words may appear to be faded or to disappear completely. As the condition progresses identifying fine details may be more difficult, such as reading the time on a watch or recognizing faces of people.
While there is currently no cure for Dry AMD research has shown that there are certain things which can decrease the risk of developing AMD. People at risk of developing AMD should (where applicable) cease smoking, eat a healthy balanced diet and use spectacles, sunglasses or contact lenses with UV protection.
The age related eye disease studies (AREDS I and II) found that taking a specific multivitamin formulation could reduce the risk of progression of AMD. It is crucial to identify changes in the retina early to reduce the risk of developing AMD.
Fundus Autofluorescence (FAF) imaging is a special type of retinal photography which can identify areas of the retina which are not functioning properly, it can be used to identify areas of change before any signs of deposit build up are evedent.
Spectral domain OCT scanning is used to examine the deeper layers of the retina to identify any build up of deposits or fluid which could lead to vision loss
Currently two Phase III trials are being carried out on a drug called Lampalizumab. It is hoped that by inhibiting the actions of a complement protein that this drug could slow the rate of progression of geographic atrophy. A phase II study found that Lampalizumab reduced the progression of GA by as much as 20% compared to a placebo.
