Age related macular degeneration Flashcards
(7 cards)
Describe the pathophysiology of dry age related macular degeneration [+]
Two types:
Wet (also called neovascular), accounting for 10% of cases
Dry (also called non-neovascular), accounting for 90% of cases:
- This phase of AMD is characterised by the presence of asymptomatic drusen formation in Bruch’s membrane.
- Drusen are small yellowish deposits which are visible on fundoscopy
- As AMD progresses, other pathological changes, including pigmentary changes in the retinal pigmentary epithelium (RPE) and geographic atrophy (Figure 3) develop
Describe the pathophysiology of wet age related macular degeneration [+]
Wet AMD is characterized by the formation of a choroidal neovascular membrane made up of new, aberrant blood vessels underneath the retina
- This is driven by vascular endothelial growth factor (VEGF)
- more rapidly progressive loss of vision, either by exudate from the new, leaky vessels or by haemorrhage.
- leakage of serous fluid and blood can subsequently result in a rapid loss of vision
Risk factors for age related macular degeneration?
Smoking
Age
FH
CVD
HTN
Describe the clinical features of ARMD
a reduction in visual acuity, particularly for near field objects
* gradual in dry ARMD
* subacute in wet ARMD
difficulties in dark adaptation with an overall deterioration in vision at night
fluctuations in visual disturbance which may vary significantly from day to day
they may also suffer from photopsia, (a perception of flickering or flashing lights), and glare around objects
visual hallucinations may also occur resulting in Charles-Bonnet syndrome
How would you investigate ARMD? [4]
slit-lamp microscopy is the initial investigation of choice, to identify any pigmentary, exudative or haemorrhagic changes affecting the retina which may identify the presence of ARMD.
This is usually accompanied by colour fundus photography to provide a baseline against which changes can be identified over time.
fluorescein angiography is utilised if neovascular ARMD is suspected, as this can guide intervention with anti-VEGF therapy.
- This may be complemented with indocyanine green angiography to visualise any changes in the choroidal circulation.
ocular coherence tomography is used to visualise the retina in three dimensions because it can reveal areas of disease which aren’t visible using microscopy alone.
Mx of ARMD?
anti-VEGF agents include ranibizumab, bevacizumab and pegaptanib
- the agents are usually administered by 4 weekly injection.
laser photocoagulation does slow progression of ARMD where there is new vessel formation, although there is a risk of acute visual loss after treatment, which may be increased in patients with sub-foveal ARMD. For this reason anti-VEGF therapies are usually preferred.
How do you differentiate between ARMD and glaucoma? [2]
TOM TIP: Glaucoma is associated with peripheral vision loss and halos around lights.
AMD is associated with central vision loss and a wavy appearance to straight lines.
