Age-related macular degeneration Flashcards
What can age-related macular degeneration (AMD) cause?
devastating los of central vision in the ageing population
What is the commonest cause of blind and partial sight in the UK In the over 60s?
age-related macular degeneration
What will happen to numbers of AMD with time?
increase as population lives longer
Do patients go completely blind in AMD?
no - peripheral vision maintained
What are 4 symptoms of AMD?
- gradual loss of central vision 2. distortion usually first symptom 3. eventually severe loss of central field but maintain peripheral navigational vision 4. difficulty with reading, recognising faces
What is speed of onset of loss of vision like in AMD?
may be very slowly progressive over years, but may have sudden deterioration if associated with haemorrhage
What kind of chart can be used to assess for central distortion from macular disease?
Amsler chart (look up image)
What are the 2 types of AMD?
- Dry (atrophic) macular degeneration 2. West (neovascular/exudative) macular degeneration
What is usually the first symptom that appears in age-related macular degeneration?
central distortion
Which is the more common form of AMD?
Dry AMD - 90%
What is the classic lesion in dry AMD?
geographic atrophy causing severe central vision loss
IS there any treatment for dry AMD?
no - nothing can halt or reverse relentless progression of dry AMD-related vision loss
What is the pre-cursor lesion leading to the development of geographic atrophy in dry AMD?
small yellowish macular lesion called drusen
What are the 2 types of drusen?
Soft and hard
What are soft drusen like? (look at photos)
pale yellow and large with ill-defined margins
What are soft drusen a sign of?
over 55 - especially larger than 63 microns - sign of age-related maculopathy
What are hard drusen like? (look at photos)
round, yellow with well-defined boundaies
How common are hard drusen?
relatively common, not always associated with AMD
Which type of drusen evolves to macular degeenration?
soft (not hard)
How does wet AMD compare in severity and frequency to dry AMD?
wet AMD is less common but more severe
What proportion of all AMD is wet AMD?
10%
What proportion of all blindness from AMD is due to wet AMD?
90%
What is wet AMD characterised by (not present in dry AMD)?
choroidal neovascularisation (CNV), development of abnormal blood vessels beneath the retinal pigment epithelium (RPE) layer of the retina
How can CNV be identified?
Fundus fluoroscein angiograph (FFA)
What happens in CNV?
new blood vessels penetrate into the retina in the macular region and bleed, which eventually causes macular scarring which can result in profound loss of central vision (disciform scar)
How many people in the UK have CNV due to AMD?
233 000; 21 000 new cases diagnosed every year
What type of scar is produced in wet AMD?
Disciform scar
How long could most eyes with AMD due to CNV under fovea be legally blind after?
2 years after diagnosis (many within months if left untreated)
Look at what wet AMD CNV looks like, and the disciform scar it can develop into.
big yellowy grey patch that develops after neovascularisation
What can drusen evolve from and to?
they can evolve from hard drusen to soft drusen
How can hard drusen forming soft drusen lead to a certain type of AMD?
hard drusen increase in number, size and confluence to eventually evolve to dry or wet macular degeneration
What is the 5-year risk of a person who is 80 years or older with soft indistinct drusen and pigmentary changes of developing macular degeneration?
42%
What is the risk that you will develop retinal changes of early maculopathy if you are <60 years with a normal retina?
0.2%
What is the risk of developing retinal changes of early maculopathy if you are over 80 with a normal retina?
22.5%
What is the risk of developing AMD in the other eye if there is AMD in one eye?
39-55%
Explain how AMD progresses.
- Normal macula, hard drusen, no maculopathy –> - soft drusen with/without pigment changes = early AMD. - goes to EITHER: X geographic atrophy (dry AMD) OR X CNV and disciform scar (wet AMD)
What are 4 strong risk factors for AMD?
- older age 2. smoking 3. positive family history 4. genetic: complement factor H (CFH) gene determined to be strongly associated with a person’s risk for developing AMD
What are 2 further *possible* risk factors for AMD?
- sunlight 2. cardiovascular
What are 5 aspects of treatment are there for dry AMD?
- Usually nil
- Low vision aids (magnifiers) to help reading
- Vitamins: only in patients with advanced AMD in one eye, high doses of zinc and antioxidant vitamins (vitamin C, E, beta-carotene [not smokers]) helps prevent advanced disease and deterioration of vision in the other eye
- Severely visually impaired (blind)/ visually impaired (partial sight) registration for assessment by authorities and benefits payments
- Social support
When was the first treatment for wet AMD developed, and what was it?
2003 (photodynamic therapy with verteporfin)
What 2 new treatments have been developed for wet AMD, after photodynamic therapy?
- Ranibizumab (Lucentis) 2. Bevacizumab (Avastin)
What difference is there between ranibizumab and bevacizumab for WET AMD?
none but bevacizumab much cheaper
What has been implicated as a key mediator in the pathogenesis of blood vessel growth and leakage in wet AMD?
VEGF-A
Therefore, how do ranibizumab and bevacizumab treatments work?
Monoclonal antibody fragments (Fab) that are non-selective VEGF-A inhibitors
How is ranibizumab for wet AMD administered?
multiple intravitreal injections into vitreous cavity
What is the result of using VEGF inhibitors for AMD (ranibizumab/lucentis or bevacizumab/avastin)?
2-year course stabilises condition and in some cases can even restore some vision
How much do injections of ranibizumab for wet AMD cost?
£1000 per injection
How can the response of anti-VEGF injections for wet AMD be measured?
- Patients require repeat examination one month after every injection
- At each visit, visual acuity is measured preferably using the logMAR scale
- fundal examination (fundoscopy)
- Repeat OCT always performed
- if any sign of new disease progression, repeat injections are arranged
What is aflibercept (Eylea)?
treatment approved by NICE; soluble VEGF receptor fusion protein which binds to all forms of VEGF-A, VEGF-B
How is aflibercept given?
monthly by intravitreal injection for 3 consecutive doses, followed by 1 injection every 2 months
How are intravitreal injections given?
Performed either in clean room or theatre under topical anaesthetic as day case
What are 3 key risks of anti-VEGF intravitreal injections?
- Endophthalmitis 2. Intraocular haemorrhage 3. Retinal detachment
How do drusen cause macular degeneration?
kills photoreceptors in that area
How does CNV cause wet macular degeneration?
Kills photoreceptors in that area due to new vessels forming and bleeding in the retina
What is the length of the course of intravitreal VEGF injections for wet AMD?
2 years
What are 2 key examinations that should be performed in suspected AMD?
- Visual acuity: Snellen chart
- Fundoscopy
What visual acuity would be recorded from the patient’s view of the Snellen chart at 6m (see image)?
6/18: viewed from 6m, can read to line labelled 18 (i.e. individuals with normal vision can read this line at 18m)
How could the image, found on fundoscopy, be described?
Haemorrhages and exudation at the centre of the macula
What could be 3 differentials for wet AMD?
- Dry AMD
- Cataract: gradual loss of vision in elderly, but throughout visual field not just centre. Onset over many months and years; misty, cloudy vision but no distortion
- Retinal vascular disease: CRAO/CRVO cause sudden loss of vision, BRAO/BRVO - may cause sudden loss of vision
What is another name for wet AMD due to the way it comes about?
Neovascular macular degeneration, due to ingrowth of new blood vessels under the retina
What happens to the new blood vessels formed in wet AMD?
bleed and leak fluid causing subretinal accumulation of fluid, subretinal blood (between RPE and Bruch’s membrane), macular oedema and subsequent subretinal scarring and fibrosis
Where are the yellow deposits that form drusen deposited in dry AMD?
between Bruch’s membrane and retinal pigmented epithelium
Which 2 investigations would be most appropriate in suspected wet AMD?
- Fundus fluorescein angiogram (FFA)
- Ocular coherence tomography (OCT)
What is OCT?
non-invasive imaging technique that uses scattering of laser light to produce a cross sectional view of retina (see healthy example in image)
What is FFA?
IV injection of fluorescein allows visualisation of the retinal vasculature, and pathological new vessels under the macula.
What are the pros and cons of FFA?
Gives a detailed view of retinal circulation
Time consuming and risk of anaphylactic reaction to fluorescein
What is shown in the image?
FFA showing subretinal leakage of dye from neovascularisation, causing area of hyper-fluorescence at macula in wet AMD
What are 3 aspects of treatment for wet AMD?
- Anti-VEGF injections
- Dietary advice: healthy diet containing anti-oxidants may help prevent, supplements including lutein and xanthine in selected cases
- Supportive treatment: low vision aid assessment for appropriate use of magnifiers & registration as visually impaired (partially sighted) or severely visually impaired (blind) → assessment from local authorities and benefits payments
How can patients with wet AMD be expected to respond to anti-VEGF injections?
Rule of thirds: 1/3 vision improves, 1/3 vision stays the same, 1/3 vision continues to deteriorate
What is the general regimen of anti-VEGF injections for wet-AMD?
Intravitreal injections given under LA, most patients require multiple given at roughly monthly intervals.
All patients require loading doses of 3 injections and on average 7 injections per year
What is the LogMAR scale?
Newer way of measuring visual acuity than Snellen chart; is similar but more accurate, was initially used in research. Now especially used for children and AMD clinics (see image)
What are 2 potential drawbacks of using the LogMAR scale rather than Snellen chart?
- No direct correlation with Snellen chart
- LogMAR is not intuitive as poorer vision is recorded as a higher number; 6/60 Snell = 1.00 LogMAR and 6/6 Snellen is 0.0 LogMAR
