AMD classification 1 and referral 2 Flashcards
What is the impact of AMD?
- Complete central scotoma
- Increased depression
- Increased falls, social isolation ect
How big is the macula?
Centre of the fovea spanning over to near the edge of the optic disk!
15-20 degrees visual angle
What is the Beckman’s grading scale for no AMD?
- No apparent aging change - nothing
- Normal aging changes - duplets. Smaller then 63 mircons
What is the classification for Beckman’s grading scale for early AMD?
Medium size drusen bigger then 63 microns but smaller then 125
NO pigmentation abnormalilties
What is the classification for Beckman’s grading scale for Intermediate AMD?
Bigger then 125 microns and/or amd pigmentary changes
What is the classification for Beckman’s grading scale for Late AMD?
Neovas (WET)and Georgraphic artophy (DRY)
(px will have Loss of central vision)
This is the only time ive been lazy, i cba to type it out, just memorise it
What is drusen?
This is local deposits between the RPE and bruchs membrane. They are waste material.
What is a psudeodrusen?
Between the reitina and the RPE
(on top of RPE)
drusen are below RPE
What are hard drusen?
Smaller than 63 microns. This is the smallest type of drusen.
Are hard drusen normal?
Yes in the aging population. but lots can lead to soft drusen
What is soft drusen?
Larger and they coalesce to form confluent drusen and are a hallmark for AMD. They have distinct or indiscint margins.
The larger and more confluent there is a higher risk of advanced AMD
What is the chance of getting foveal atrophy or choroidal neovascularisation if you have bilateral drusen?
3% per eye.
What increases the chance of advanced AMD a lot?
Larger drusen and pigmentary changes in both eyes increases the chances to almost 50%
What causes hyperpigmentation?
- Increased melanin in the RPE
- RPE cell proliferation (proliferation means rapid cell growth)
- RPE cell migration (this means when the cells are movings somewhere!)
What causes hyperpigmentation?
- Increased melanin in the RPE
- RPE cell proliferation (proliferation means rapid cell growth)
- RPE cell migration (this means when the cells are movings somewhere!)
How does hypopigmentation look on fluorescence imaging ?
It will be glowing patches, because there is less pigment to block it.
What causes hypopigmentation?
- Reduced melanin content
- Rpe cell atrophy
- Rpe layer thinning
What does geographic atrophy look like?
sharply outlined area of loss of pigmentation larger than 175 microns
What happens when RPE dies? (GA)
The photoreceptors die
The underlying chorioid will die too..
Dead areas of retina = pale areas
why are areas of fundus pale on the fundus with artophy?
Dead tissue : photocells and the choroid have died
Where does geographic atrophy normally start?
It normally starts parafovea, and then it will include the fovea eventually = central scotoma
Is geographic atrophy bilateral?
In 50% of px it is.
What is choroidal neovascularisation (wetAMD)?
This is new choroidal blood vessels growing beneath the RPE or the subretinal space.
Can be seen as a green or grey region
What will CNV look like on OCT?
Hyperreflective lump under the RPE
What is the prevelance of wet amd?
15% of px with early amd will get wet amd
What other findings are common with wet amd?
- Sub or intraretinal haemorrhages
- Hard exudates
- Intra-retinal fluid
- Sub-retinal fluid
- Pigment epithelial detachment is common
What is a disciform scar?
This is when there is repeated leakage of blood, serum and lipid.
It will stimulate a scar tissue to form
What is the vision loss like in wet AMD?
It is normally a rapid loss of vision
Why do we get vision loss in WET amd?
- Exudates
- Haemorrhages
- Secondary cell death
- Disciform scar
When we want to treat wet AMD?
Before the scar tissue forms!!! As the scar tissue is irreversible.
What causes wet AMD?
Inflammation and hypoxia will stimulate growth factors —> VEGF
What is pigment epithelial detachment?
Detachment between the basement of the RPE and bruchs membrane.
It can reattach but it can also tear
What does pigment epithelial detachment (PED) cause?
It will leave areas of atrophy and subretinal fibrosis
What is linked to PED linked too?
Choroidal neovas = 80%
What makes the other 20% chance of PED?
Drusen stopping fluid leaving the retina to the choroidal circulation leads to a build of fluid under the RPE
what will PED look like on the OCT?
There will a dome like elevation.
We know it is not a RD as the reflective layer of the RPE is elevated!
How do we know it is a PED and not a RD?
The reflective layer of the RPE is elevated! If the RPE layer in the oct was flat then it would a RD
Features of reticular pseudodrusen (RPD)?
- This is yellow interlacing pattern
- Located between the retina and the RPE.
- This is easier seen on IR/blue light
They will have lower Vision compared to px without RPD, esp dark adaptation
What does RPD causes?
(reticular pseudodrusen)
nothing if only a few,
loads = increased risk of developing AMD!
What problem is there with oxidative damage in the eye?
- The retina is prone to oxidative damage
- The RPE cannot break down these oxidated products, therefore they accumulate
why is the retina prone to oxidative damage?
- lots of light intake
- contains lots of polyunsaturated fatty acids which have double bonds which are prone to being oxidised
How can inflammation be linked to pathogenesis of AMD?
- inflammatory cells in those with CNV, drusen RPE atrophy
- link between AMD and inflammatory cell genes (CFH)
what are the 2 theories of pathogenesis of AMD?
oxidative damage
inflammation
What is the biggest risk factor of AMD?
AGE
85+ = 30% of early and 13% for late AMD
What other factors are there?
- Ethnicity. Less in black: Melanin the darker mandem will protect the retina from oxidative damage.
- Genetic : Twins both get it normally showing it is linked. Also, first degree relatives having AMD will increase the risk of AMD, by 6-12X
- Smoking
- Light exposure. Especially blue light, but research is unclear.
- Diet
- Diabetes
- Females
- Pale iris colour
- Hypermetropia
- Alcohol
What systemic risk factors are there?
- Cataract surgery
- Cardiovascular disease
- Hypertension
- BMI
- higher plasma fibrinogen