What is Age-related Macular Degeneration?
AMD usually occurs in people over 50 years of age, and is becoming common with our ageing population and the effect on an individual’s life-style is devastating. It is an eye condition characterised by progressive and irreversible damage to the central part of the retina (the macular) resulting in loss of central vision and the ability to read and to see fine detail is lost.
70% of patients experience severe vision loss within two years. Peripheral vision is not affected, so patients may maintain navigational vision and therefore social independence.
Initial symptoms of AMD are of blurred or distorted central vision, which progresses to a blank patch or dark spot (scotoma). AMD usually affects both eyes, although one may be affected before the other, leading to delayed diagnosis as the ‘good’ eye compensates for the affected eye.
The cause of macular degeneration is unknown but it may be a combination of a genetic and environmental factors.
Age-related macular degeneration can be broadly sub-divided into two: dry (geographic atrophy) and wet (exudative) age related macular degeneration.
Dry Age Macular Degeneration (Geographic Atrophy)
Dry macular degeneration is the commonest cause of macular degeneration. It is characterised by the absence of any neovascularisation but the presence of drusen and abnormalities in the retinal pigment epithelium. Changes in the pigment epithelium are areas of atrophy, which begin as small-localised areas of loss of central vision. This process is slow and develops over a number of years. The progression of dry macular degeneration can be slowed by taking anti-oxidants. Anti-oxidants are present in many foods but it may be important to take in addition a vitamin supplement containing vitamin C, E, Zinc, Copper and possibly lutein. Some 10% of patients with dry macular degeneration will progress to the wet or neovascular age-related macular degeneration. This progression is sudden and rapid.
Wet Macular Degeneration (Neovascular ARMD)
The wet form, exudative or neovascular account for about 10% of AMD cases and is caused by a rapid growth of choroidal blood vessels through Bruchs’ membrane, which lies between the choroids and the retina and into the space under the retinal pigment epithelium. These new blood vessels then leak fluid lipid or blood into this space, they progress rapidly, destroy central vision and then attract fibrous tissue and ultimately give rise to a fibrous scar in the central retina, the process can progress rapidly within a few months and is responsible for 90% of AMD related visual disability. If wet ARMD has occurred in one eye, it frequently develops in the fellow eye with risk of approximately 30% over a five-year period.
The development of new blood vessels beneath the retina in the wet form of AMD is known as choroidal neovascularisation (CNV).
CNV can be subdivided into classic and occult forms according to its appearance on investigation by fluorescein angiography. Classic CNV is associated with more rapid progression that the occult form. Classic and occult CNV can occur within the same patient.
We can offer treatment for both Dry and Wet forms of Age-related Macular Degeneration.
Contact us for more detailed information.