ARMD Flashcards
What is the most common cause of blindness in the UK?
Age related macular degeneration (ARMD)
What is ARMD?
A progressive condition involving the degeneration of the macula.
What is the greatest risk factor for ARMD?
Increasing age
the risk of ARMD increases 3x for patients aged older than 75 years, versus those aged 65-74.
Risk factors for ARMD?
1) Increasing age
2) Smoking
3) FH
4) Increased risk of ischaemic CVD, such as HTN, dyslipidaemia and diabetes mellitus.
What are the 2 types of ARMD?
1) Dry (90%)
2) Wet (10%)
What is the role of the macula?
Found in the centre of the retina.
It generates high-definition colour vision in the central visual field.
What are the 4 layers of the macula?
1) Choroid layer (at the base)
2) Bruch’s membrane
3) Retinal pigment epithelium
4) Photoreceptors (towards the surface)
What finding is dry ARMD characterised by?
Drusen –> yellow round spots in Bruch’s membrane
What are drusen?
Drusen are yellowish deposits of proteins and lipids between the retinal pigment epithelium and Bruch’s membrane.
A few small drusen can be normal in older patients. Frequent and larger drusen can be an early sign of macular degeneration.
Does wet or dry ARMD carry a worse prognosis?
Wet
What are 2 other features common to wet and dry ARMD?
1) Atrophy of the retinal pigment epithelium
2) Degeneration of the photoreceptors
What occurs in wet ARMD?
New vessels develop from the choroid layer and grow into the retina (neovascularisation).
These vessels can leak fluid or blood, causing oedema and faster vision loss
What is a key chemical that stimulates the development of new vessels in wet ARMD?
vascular endothelial growth factor (VEGF)
Clinical features of ARMD?
1) Gradual onset of central vision loss
2) Reduced visual acuity e.g. gradually worsening ability to read small text.
3) Crooked or wavy appearance to straight lines (metamorphopsia)
4) Difficulties in dark adaptation with an overall deterioration in vision at night
5) Visual hallucinations may also occur resulting in Charles-Bonnet syndrome
Progression of wet vs dry ARMD?
Wet AMD presents more acutely than dry AMD. Vision loss can develop within days and progress to complete vision loss within 2-3 years. It often progresses to bilateral disease.
