Age-related Macular Degeneration (AMD)

Age-related Macular Degeneration (AMD) is the leading cause of blindness which affects central vision. It is a degenerative disease of the retina that if left untreated can cause complete central vision loss; affecting the ability to read or drive. AMD is a painless condition that is age related and more commonly affecting those over 50 years of age. Often the condition presents in one eye and the other retains normal vision however it is important to monitor both eyes as each year there is a 10% chance of it developing in your fellow eye (over a 5 year period this increases to a 50% chance). There are two forms of Age-related Macular Degeneration (AMD) known as WET and DRY.  They both form in a layer of cells under the retina, known as the Retinal Pigment Epithelium, or RPE. The RPE is responsible for passing oxygen, sugar and other essentials up to the retina and moving waste products down to the blood vessels under this layer of tissue into the choroid. It is when there is an increase in the build up of waste products that deposits of drusen are formed.

Drusen
Drusen forms in two stages, known as hard and soft. Hard drusen is made up of lipids and calcium. They are usually a round formation in shape and small in size. They are a sign of macular degeneration however a less sinister form. As they can change into soft drusen they increase in number and size and may become more threatening.  Soft drusen is irregular in shape, yellowish colour and can be both large and small in size.  Soft drusen may be a sign of macular degeneration as it affects the outer layer of the retina causing it to separate. When detected, a change of diet and exercise may be advised as well as adequate sunglasses to further protect the eye as there is no way of preventing AMD. Once detected, your ophthalmologist only has the ability to slow down, and in some cases stop the progress with a range of treatments.

DRY Age-related Macular Degeneration (AMD)
DRY Age-related Macular Degeneration (AMD) is the more common of the two forms of macular Degeneration and has three distinct stages; Early, Intermediate and Advanced.  Dry AMD occurs when the light sensitive cells in the macular slowly break down causing a blurring of your sight. Gradually a dark blurred spot in the central vision may be noticed. As it progresses, the blurred spot will start to increase and the macular will cease to function properly resulting in a loss of vision.Early signs may be the inability to recognise faces from a distance and requiring additional light when reading. Commonly patients have difficulty adjusting from light to dark, taking their eyes a much longer time adjusting than usual (up to five minutes).

WET Age-related Macular Degeneration (AMD)
WET Age-related Macular Degeneration (AMD) occurs when abnormal blood vessels, located behind the retina in the choroid, leak into the area above and below the photoreceptors. These blood vessels are very fragile and start to leak blood and fluid into the eye causing an imbalance of the macula and start to damage and destroy the photoreceptors (the rods and cones of the eye).  Wet AMD can occur quickly and there are no distinct stages, as with Dry AMD, however if diagnosed early enough there is a chance the vision will not deteriorate further with monitored treatment. It can also be known as Advanced AMD and early signs may be noticed when looking at straight lines and they appear to bend. To check your central vision, hold the ‘Amsler Grid’ as you would a book, and focus on the central spot. If the lines appear crooked you should contact your ophthalmologist as soon as possible.

Treatment of Dry Age-related Macular Degeneration
Currently there is no proven treatment for Dry AMD, however a clinical trial on the proven effects of a nutritional formula have been diagnosed. With the combination of a healthy well balanced diet, no smoking and wearing of correct eye protection along with a combination of vitamins has been noted to aid in preserving sight.  The Age-Related Eye Disease Study (AREDS) showed that taking a unique combination of high potency vitamins (beta-carotene, vitamin C and vitamin E) and minerals can help preserve sight by reducing the risk of associated vision loss caused by moderate to advanced AMD. According to the National Eye Institute (NEI) who conducted the AREDS study: “the effect of using only some of the antioxidants used in the AREDS study or substituting other antioxidants has not been determined” and “the individual effects of these components has not been evaluated” ¹ Your ophthalmologist will also monitor the eye regularly, with the use of the Optical Coherence Tomography (OCT) machine.

Optical Coherence Tomography (OCT)
Optical Coherence Tomography (OCT) is a non-invasive, non-contact imaging technique, used to take images of the retina and the optic nerve. By focusing beams of light into the eye it will scan a cross section image, similar to a topographical map.  This machine will not only be used in detecting and monitoring Age-related Macular Degeneration but it is also used in diagnosing other macular diseases including; macular holes, macular oedema, epiretinal inflammatory diseases and it also assists in the assessment of glaucoma as it has the ability to assess the nerve damage to the back of the eye.

Treatment of WET Age-related Macular Degeneration
In the past few years there have been advancements made in slowing down and in some cases even stopping the progression of Wet AMD. Before treatment can start on the Wet Agerelated Macular Degeneration, an Angiogram test needs to be taken to determine the best treatment for your individual circumstances. The ophthalmologist will also monitor the eye with the use of the Optical Coherence Tomography (OCT) machine as early detection is critical in order to save the patients sight.  Anti – Vascular Endothelial Growth Factor (Anti VEGF) medication is used to treat swelling of the macula that occurs in Age-related Macular Degeneration (AMD). It has increased success in inhibiting the growth of the blood vessels that cause AMD and is suitable for the majority of patients. The Anti-VEGF medication prevents the blood vessels from growing or forming, hence slowing the leakage and slowing down the vision loss. Your consultant will discuss with you the treatment and which medication they feel is best suited for you.

Photodynamic therapy (PDT)
Photodynamic therapy (PDT) is less commonly used in combination with injections. An angiogram will initially be taken to determine if a patient is suitable for PDT treatment. PDT treats the abnormal growth of the leaking blood vessels to prevent them from continuing to leak into the eye causing the AMD to advance. For the laser treatment, you will have a drop of local anaesthetic put into your eye and a contact lens is used. When the Verteporfin is activated by light it closes up the blood vessels, reducing the leakage and preventing further vision loss.  There are a series of treatments with PDT continuing over a 2 year process. When on the PDT therapy it is strongly advised to cover your limbs and stay indoors for a few days after each treatment as it is light sensitive treatment and will cause you to burn very easily.  The best treatment for your macular degeneration may be a combination of treatments and a healthy well balanced diet. Fortunately research will continue on the best treatment for wet macular degeneration giving hope to retaining some vision in a condition which without treatment typically leads to severe vision loss.