Age-related macular degeneration (AMD or ARMD) is one of the most common cause of vision loss in those aged over 50. AMD is a condition that occurs when cells in the macula degenerate. This occurs with partial breakdown of the RPE and the cells become damaged and die. Damage to the macula affects your central vision which is needed for reading, writing, driving, recognising people's faces and doing other fine tasks. The disease does not lead to complete blindness. Visual loss can occur within months, or over many years, depending on the type and severity of AMD.
In this type the cells in the RPE of the macula gradually become thin (they 'atrophy') and degenerate. This layer of cells is crucial for the function of the rods and cones which then also degenerate and die. Typically, dry AMD is a very gradual process as the number of cells affected increases. Many people with dry AMD do not totally lose their reading vision.
Wet AMD may also be called neovascular or exudative AMD. However, it is likely to cause severe visual loss over quite a short time - sometimes just months. Very occasionally, if there is a bleed (haemorrhage) from a new blood vessel, this visual loss can occur suddenly, within hours or days. In wet AMD, in addition to the retinal pigment cells degenerating, new tiny blood vessels grow from the tiny blood vessels in the choroid. This is called choroidal neovascularisation.. These vessels are fragile and tend to leak blood and fluid. This can damage the rods and cones, and cause scarring in the macula, causing further vision loss.
AMD is painless. Symptoms of dry AMD tend to take 5-10 years to become severe. However, severe visual loss due to wet AMD can develop more quickly.
ARMD is usually diagnosed after an eye specialist (an ophthalmologist) examines the back of your eye, using an ophthalmoscope. The retina at the back of your eye has a typical appearance in ARMD.
Your specialist may advise some other tests or examinations to help to see how much damage has occurred to your retina. The tests may include:
For the more common dry AMD, there is no specific treatment yet. There are, however, certain things that can be done to maximise the sight you do have and to improve your eye health. Low vision rehabilitation and low vision services may help to improve potential vision. Stopping smoking and protecting the eyes from the sun's rays by wearing sunglasses are important. A healthy balanced diet rich in antioxidants may be beneficial, as may the addition of dietary supplements (see below for details). Remember that in this type of AMD the visual loss tends to be gradual, over 5-10 years or so.
For the less common wet AMD, treatment may halt or delay the progression of visual loss in some people. Newer treatments may even be able to reverse some of the visual loss. Treatments which may be considered include treatment with anti-vascular endothelial growth factor (anti-VEGF) medicines, photodynamic therapy and laser photocoagulation.
Anti-VEGF therapy (Avastin, Lucentis, Ozurdex)
Anti-VEGF therapy involves the injection of the medication into the back of your eye. The medication is an antibody designed to bind to and remove the excess VEGF (vascular endothelial growth factor) present in the eye that is causing the disease state. The FDA has approved Lucentis for macular edema and additional treatment options include Avastin and Ozurdex.
A medicine called verteporfin is injected into a vein in the arm. Within a few minutes the verteporfin binds to proteins in the newly formed abnormal blood vessels in the macula. A light at a special wavelength is then shown into the eye for just over a minute. This means that when light is shown at the blood vessels coated with verteporfin, the verteporfin activates and causes damage, destroying the abnormally growing blood vessels (neither damaging the nearby rods and cones, nor any normal blood vessels).
Photodynamic therapy is only suitable for some cases. It depends on exactly where the new blood vessels are growing and their extent. Treatment usually needs to be repeated every few months to continue to suppress newly growing blood vessels.
Dr. Shrutika Kankariya
Retina & Diabetes Eye Specialist MBBS (KEM,Mumbai), DNB (Sankara Nethralaya, Chennai),FRCS(Glasgow), FICO(UK), Fellow Retina (Sankara Nethralaya & USA),