Age Related Macular Degenerstion Flashcards
What is AMRD?
Degeneration of the central retina (macula), this is the key features with changes usually bilateral.
ARMD is characterised by degeneration of retinal photoreceptors which results in the formation of drusen which can be seen on fundoscopy and retinal photography.
What are the two types of ARMD?
Dry (90% of cases, geographic atrophy) macular degeneration- this is characterised by drusen (yellow round spots in Bruchs membrane)
Wet (10% of cases, exudative and neovascular) macular degeneration- characterised by choroidal neovascularisation
Leakage of serous fluid and blood can subsequently result in a rapid loss of vision. It carries the worse prognosis
What is the epidemiology of ARMD?
The male: female ratio is 1:2
The average age of presentation is greater than 70 years of age
What are the risk factors for age related macular degeneration?
Advancing age is the greatest risk factor for ARMD (3x fold for patients over 75 compared to those 65-74)
Smoking (2x more likely)
Family history (first degree relatives of a sufferer of ARMD are 4x more likely to inherit the condition)
Increased risk of ischaemic CVD (hypertension, dyslipidaemia, diabetes mellitus)
What are the signs of age related macular degeneration?
Reduction in visual acuity, particularly for near field objects
Difficulties in dark adaptation with an overall deterioration in vision at night
Fluctuations in vision day to day
They may have photopsia (flickering or flashing lights) and a glare around objects
What are the signs of ARMD?
Distortion of line perception may be noted on Amsler grid testing
Fundoscopy reveals the presence of drusen
In wet ARMD well demarcated red patches may be seen (represent intra retinal or sub retinal fluid leakage or haemorrhage)
What are the investigations of age related macular degeneration?
Slit lamp microscopy= initial investigation of choice
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.
What are the four layers of the macular?
Choroid
Bruchs membrane
Retinal pigment epithelium
Photoreceptors
What is Drusen?
Yellow deposits of protein and lipids which appear between the retinal pigment epithelium and Bruch’s membrane
Some drusen can be normal, normal drusen is small and less than 63 micrometres and hard whereas larger and greater numbers of drusen can be an early sign of macular degeneration
Other than drusen, what other features are present in AMD?
Atrophy of the retinal pigment epithelium
Degeneration of the photoreceptors
What is the pathophysiology behind wet AMD?
There is development of new vessels growing from the choroid layer into the retina, these vessels can leak fluid or blood and cause oedema and more rapid loss of vision
A key chemical that stimulated the development of new vessels is VEGF and this is the target of medications to treat wet AMD
What are the risk factors for AMD?
Age Smoking White or chinese ethnic origin Family history Cardiovascular disease
What is the presentation of ARMD?
Gradual worsening central visual field loss
Reduced visual acuity
Crooked or wavy appearance to straight lines
What is more acute, wet or dry AMD?
Wet age related macular degeneration presents more acutely, it can present with a loss of vision over days and progress to full loss of vision over two to 3 years, it often progresses to bilateral disease.
What is scotoma?
A central patch of vision loss
