AMD Flashcards
What is AMD?
Eye condition which affects the central retina causing vision ,oss
What is the macula and how big is it ?
The central area of the posterior pole, subtends an area of 15-20 degrees.
What is the fovea?
The fovea is right at the centre of the macula subtending an area of 5 degrees of your visual field.
What areas surround the fovea?
Surrounding the fovea is the parafovea and the perifovea is around the parafovea.
From centre going out, name the structures of the central retina
Fovea-parafovea-perifovea-macula
What are the non-modifiable risk factors of AMD?
Age >50
FH
Genetic
What are the modifiable risk factors of AMD?
Smoking
HTN, High fat diet, Lack of exercise
Cataract sx
How does cataract surgery affect AMD?
Can be a risk for speeding up any AMD present.If a px has any signs of AMD they’ll be made aware of the risk of it progressing more quickly if they have cataract surgery)
Give 5 tests you can do in a suspected AMD px
BCVA – ETDRS chart
Amsler
Reading speed
Mircoperimetry/gross perim = field test for central vision loss
Fundus BIO and OCT
What are the 2 symptoms of dry AMD?
Reduced VA
Distortion on amsler
What are the 3 symptoms of wet AMD?
Sudden onset of distortions and reduced vision in the affected eye.
Why may the symptoms of wet AMD go unnoticed?
This may not be immediately notice if the fellow eye is unaffected, which is why patients at risk of wet AMD are advised to monitor their vision monocularly on a daily basis.
What is the very first sign of AMD?
Drusen
What are the signs of early AMD?
Soft drusen ≥63µm
RPE hyper/hypo pigmentation
RPE atrophy(cell death)
What are the signs of late dry AMD?
Geographic atrophy (GA)
Sharply demarcated area of atrophy
What is another name for dry AMD?
Atrophic/non-neovascular
What are the signs of wet AMD?
Choroidal neovascularisation
Macular oedema
SRF=sub retinal fluid
Haemorrhages=Sub, intra or pre retinal
Serous detachment of neurosensory retina
RPE detachment (PED) or tear
Exudates
Scarring (disciform)(a neovasuclar scar can form)
What are basal laminar deposits?
An sign of early AMD
Lipid deposition in Bruch’s membrane
What causes basal laminar deposits to form?
Failure of RPE to process cell debris
How are basal laminar deposits seen?
Using electron microscopy so you won’t be able to use OCT to see it
What are drusen?
Earliest visible sign
Round yellow deposits
Where are drusen located?
Between RPE and bruch’s membrane
What are drusen made of?
Deposits of lipofuscin, amyloid, complement factors so they’re waste products
How can drusen be described?
Size:
Small <63µm= Very common, ~80% >age 30 yrs
Large ≥63µm=Hallmark of AMD, 26% >age 70 yrs have large drusen
Apperance:
Hard, soft or confluent
What is the difference between Hard, soft or confluent drusen?
Hard drusen have well defined margins and soft drusen have ill define margins.
Confluent is combination of both
How can u measure drusen?
- On a fundus photograph using suitable tools
- On OCT which have calaerpers and can measure the width of the drusen
When is drusen normal vs abnormal?
Hard drusen in small numbers= part of normal ageing process/NOT AMD
When numerous hard drusen present= risk factor for soft drusen and AMD
What are pigmentary changes caused by?
Increased melanin content of RPE, RPE cell profileration, RPE cell migration.
What is geographic atrophy?
GA are regions of RPE cell death causing death of photoreceptors causing scotoma
Inner retinal layer then start to die too
How fast is the vision loss with GA occuring?
Gradual loss of central vision leads to eventual scotoma.
How is GA seen in a hospital?
Increased autofluorescence on Fundus Autofluorescence.
What are the two features that increase the risk of progression to wet AMD?
Larger, increased number and more confluent drusen with pigmentary changes associated with increased risk progression to advanced AMD
Signs of WET AMD?
Choroidal neovascularisation
Macular oedema
SRF=sub retinal fluid
Haemorrhages=Sub, intra or pre retinal
Serous detachment of neurosensory retina
RPE detachment (PED) or tear
Exudates
Scarring (disciform)(a neovasuclar scar can form)
What causes choroidal neovascularisation?
Hypoxia caused by deposits build up leads to choroidal neovascularisation (haemorrhages which leak under RPE, or subretinal space causes RPE detachment, leaves area of atrophy).
What can repeated leakage cause?
Repeated leakage form disciform scar-complete scotoma/untreatable. Macular oedema, exudates
How does CNV appear on fundus?
CNV may be seen as a green/grey lesion on a fundus photograph
But is easier to detect either using as binocular stereoscopic viewing strategy, such as volk, or on OCT, where the disrupted, raised RPE is clearly visible, and the hyperreflective neovascular membrane is seen beneath
What are the first symptoms of wet AMD?
Sudden onset of distortions and reduced vision in the affected eye. This may not be immediately notice if the fellow eye is unaffected, which is why patients at risk of wet AMD are advised to monitor their vision monocularly on a daily basis.
Can you get CNV in early AMD?
Yes, CNV develops in 10-15% of people with early AMD.
Why causes sub or intraretinal haemorrhages, hard exudates, intra-retinal fluid, or retinal pigment epithelial detachment to form?
The fragile nature of the new vessels means that sub or intraretinal haemorrhages, hard exudates, intra-retinal fluid, or retinal pigment epithelial detachment are common.
Where are these new blood vessels growing from and where do they grown into?
From the choroidal circulation, through breaks in Bruch’s membrane, to proliferate beneath the RPE. They can also break through the RPE to grow into the subretinal space.
What causes a PED in wet AMD?
It’s a separation which occurs between the basement membrane of the RPE and Bruch’s membrane.
What is the prognosis of a PED?
May flatten over time, but 1 in 10 is also likely to tear.
Either way, the prognosis is poor, and the PED usually leaves an area of atrophy or subretinal scar tissue formation.
How do you differentiate wet AMD from hypertensive retinopathy?
CNV leakage causes exudate in the area so it can start to look hypertensive retinopathy.
The difference is that Wet AMD is confined to the macula area and it can be bilateral so look in ur history and symptoms whether px has told u that they have hypertensive ret or high blood pressure
What are the main symptom differences between dry and wet?
DRY= Gradual loss in central vision, amsler distortion may be reported in later stage
WET=Sudden painless loss in central vision, monocular likely but can be binocular, distortion
