DIS - Macular Diseases I: AMD - Week 1 Flashcards
True or false
AMD is the most prevalent macular disorder in Australia?
True
Is the prevalence of AMD projected to increase or decrease? Explain why.
Increase due to growing elderly population
Is AMD a bilateral disease? Explain.
Usually affects one eye, but is a bilateral disease - eventually
What do photoreceptors shed? What happends to these and by what?
Shed outer segment discs
RPE enzymes degrade and recycle them
What happens to light-damaged elements shed by the photoreceptors? What do they form and what do they coalesce to form?
Light damaged outer segment discs cannot be degraded/recycled.
They form lipofuscin vesicles
These coalesce to form BLamD
How can BLamD be visualised?
FAF
Where do BLamD accumulate? What happens to them eventually (forming what)?
They accumulate at the basement membrane of the RPE
They are shed by the RPE and form BLinD
What are druplets?
BLinD
What do druplets coalesce to form?
Drusen
Where does reticular drusen form? Is it more or less serious than other forms of drusen?
Forms at the inner surface of the RPE (interface with the photoreceptors)
More serious
What keeps the choriocapillaris active and what is it produced by?
Kept active by cytokines produced by the RPE
Collectively, what do BLamD, BLinD, and drusen do (2)?
Restrict the RPE, reducing bruch’s membrane flow
What is reticular drusen also known as?
Pseudo-drusen
What happens to BLinD with age? What happens to bruchs membrane alongside this? What consequence does this have?
It thickens
Bruchs membrane takes up cholesterol from the blood - forms plaques
Further restricts clearance and exchange of RPE
Consider what happens to BLinD with age. What happens to the choriocapillaris as a result and what is the consequence of this?
It fails to get PEDF/VEGF and atrophies
What promotes an immune response at bruch’s membrane? List two causes of this. Explain how these two result in either wet or dry AMD.
Lack of proper cytokine/metabolite exhcange:
Genotype for factor H
-increases inflammation, resulting in wet AMD
Complement suppression
-decreases inflammation, resulting in dry AMD
How do cholesterol plaques affect bruchs membrane’s function?
Cholesterol coats BLinD, which reduces BM hydraulic conductivity
What is cholesterol trafficking promoted by and how do genetics of this affect AMD?
Promoted by apo-lipoproteins
People with genetic variants in APoE get faster/worse AMD
What does being factor H positive promote?
RPE apoptosis
List 5 factors for AMD.
Age
Smoking
Fellow eye with AMD
RPE disruption (RPE disorders)
Genotype for factor H/ApoE
Can diet affect AMD risk? Consider carotenoids, antioxidants and fats (2).
Carotenoids and antioxidants confer protection
Saturated fats promote progression
High Omega-3 PUFA confers protection
Can high dose antioxidants and/or minerals reduce progression early in AMD or is the eivdence poor?
Reduces progression by 25%
In what colour eyes is AMD more common? Give a possible reason why.
More common in blue eyes
-light damage - oxidation
What race and gender is more at risk of AMD? Is gender a risk?
Caucasian
Female
-not a risk factor after longevity is considered
What proportion of AMD cases are wet and dry?
Wet - 15%
Dry - 85%
List the four stages of AMD.
1 - druplets and drusen
2 - RPE sress, pigment irregularities
Dry - atrophic/non-exudative
Wet - exudative
What is RPE stress best visualised by? How does it appear?
Fundus autofluorescence (FAF)
-appears as dropout zones
Can atrophic areas of the RPE develop anywhere in the macula or only specific areas?
Anywhere
What is dry AMD characterised by? What kind of vision loss occurs, if any?
Apoptosis of the RPE, giving geographic atrophy
Results in slow, very profound vision loss
What size of geographic atrophy is clinically significant?
> 0.5DD
What does the inflammaotry overlay of wet AMD promote (3)? What kind of visiion loss does this result in?
Choroidal neovascularisation (CNVM)
Leakage of blood/fluid from
CNVM
Serous RPE detachment
Results in acute profound vision loss
What happens to wet AMD over time?
Gives a fibrous scar - disciform degeneration
What are the four clinical classifications of AMD based on appearance?
Drusen size (not number)
Presence of pigmented abnormality
Fellow eye status
Other modifying factors
Describe how drusen size is classified and note within what distance to the fovea.
Drusen within 2DD of the fovea:
Small - druplet <63 microns
- <1/4 BV
Intermediate - 63 - 125 microns
- <1/2 BV
Large - >125 microns
- size of a vein at the disc
How do reticular drusen appear (2)?
Dark craters with a central spot
Are reticular drusen high or low risk?
High risk
What image is needed to score AMD? Is it for the eye or for the person?
Use colour fundus photography
Score is for the person, not the eye
Score each drusen within 2DD of the fovea
List the scoring for AMD (criteria for each) and the maximum score (5).
Hyper/hypo/disrupted pigment areas >1/4DD
Large drusen >125 microns
Presence of reticular drusen
Presence of bilateral intermediate drusen
Presence of end-stage AMD in fellow eye (wet or dry)
Each criteria met is 1 score
Max score of 4 for any person (R+L)
Descibe how to interpret risk scores for AMD.
0 - very low
1 - low
2 - moderate
3 - high
4+ - very high
Describe the risk of AMD progression for each risk score.
0 - 0.5%
1 - 3%
2 - 12.5%
3 - 25%
4 - 50%
-progression over 5 years, 10 years is similar percentage
How should you manage individuals with an AMD risk score of 0 or 1 (2)? Include review schedule.
2 year reviews with CFP/OCT
Antioxidants for 1+
How should you manage individuals with an AMD risk score of 2 (3)? Include review schedule.
1 year reviews with CFP/OCT
Home monitoring
Antioxidants for 1+
How should you manage individuals with an AMD risk score of 3 (3)? Include review schedule.
6 month reviews with CFP 12/12 and OCT 6/12
Home monitoring
Antioxidants for 1+
How should you manage individuals with an AMD risk score of 4 (3)? Include review schedule.
3 month reviews with CFP 12/12 and OCT 3/12
Home monitoring
Antioxidants for 1+
What are 2 options for home monitoring AMD?
Amsler - poor option
Tablet/smart phone
At what risk score should antioxidant use be promoted?
1+
What are patients with iAMD or advanced AMD in one eye recommended to take and why?
AREDS supplements to reduce risk of progression to advanced AMD (25% over 5 years)
