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.
Vision loss in glaucoma vs ARMD?
Glaucoma –> peripheral vision loss, halos around lights
ARMD –> central vision loss, wavy appearance to straight lines
Key findings on examination in ARMD?
1) Reduced visual acuity using a Snellen chart
2) Scotoma (an enlarged central area of vision loss)
3) Amsler grid test can be used to assess for the distortion of straight lines
4) Drusen may be seen during fundoscopy
What can be used to assess for the distortion of straight lines seen in ARMD?
Amsler grid test
What does fundoscopy reveal in ARMD?
Drusen
What is the initial investigation of choice in ARMD?
Slit lamp microscopy - gives a detailed view of the retina and macula.
What investigation is used for diagnosing and monitoring ARMD?
Optical coherence tomography - gives a cross-sectional view of the layers of the retina
What invesetigation can be used to assess oedema and neovascularisation in wet ARMD?
Fluorescein angiography - involves giving a fluorescein contrast and photographing the retina to assess the blood supply
Mx of dry ARMD?
No specific treatment, reduce risk of progression:
1) avoid smoking
2) control BP
3) vitamin supplementation
What medications are used to treat wet AMRD?
Anti-VEGF e.g. ranibizumab, aflibercept and bevacizumab
Role of anti-VEG medications in wet ARMD?
Block VEGF and slow the development of new vessels.
They are injected directly into the vitreous chamber of the eye (intravitreal), usually about once a month.
