Age related macular degeneration Flashcards
What can AMD cause?
gradual loss of central visual field
= most commonest cause of blind and partial sight registration in the western world
Do NOT go completely blind, and maintain independence as peripheral vision is maintained
Which age group is most affected by AMD?
typically >60s with incidence increasing sharply after 80
- with increasing ageing population prevalence is going to increase
AMD in one eye means there is a 50% chance of the other eye becoming affected
What is normally the first symptom?
distorted vision, eventually leading to severe loss of central visual field with difficulty reading and recognising faces
When can the deterioration be sudden?
If associated with haemorrhage - this is Wet AMD
What are the risk factors for AMD?
increasing age
smoking
family history
possibly sunlight and cardiovascular disease (hypertension, hypercholesterolaemia, obesity)
What is the pathogenesis of AMD?
accumulation of drusen within the macula, they start off hard and then progress to soft
What are hard drusen like?
round, yellow and well-defined - they are common and not necessarily associated with AMD
What are soft drusen like?
pale yellow, large and ill-defined
They evolve and increase in size, number and confluence to eventually become dry or wet AMD
What do the drusens do in dry AMD?
Atrophic macular degeneration
- most common type
soft drusen lifts up the pigment epithelium of the retina, causing atrophy of the photoreceptors
- geographic atrophy causing severe central vision loss
What do the drusens do in wet AMD?
neovascular/exudative
abnormal growth of blood vessels from choroid into region of soft drusen (retina) causing bleeding
What is the treatment for dry AMD?
usually no treatment so progression cannot be halted or prevented
- low vision aids can be used to help reading
- vitamins are used in advanced stages (high dose zinc and antioxidants)
- social support and blind/partial sight registration is important
What is wet AMD characterised by?
choroidal neovascularisation - development of abnormal blood vessels beneath the retinal pigment epithelial layer of the retina
How can choroidal neovascularisation be identified?
identified on fundus fluorescein angiography - growth of new vessels can penetrate into the macular region of the retina and bleed - bleeding of vessels will eventually cause macular scarring
What is the consequence of the scarring in CNV?
the disciform scars can result in a profound loss of central vision
How is wet AMD treated?
non-selective VEGF-A inhibitors - ranibizumab / bevacizumab
- VEGF-A is a key mediator in the pathogenesis of blood vessel growth and leakage
