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0V2022 Introduction to eye diseases > age-related macular degeneration > Flashcards

age-related macular degeneration Flashcards

1
Q

what is AMD?

A
  • degenerative disorder of the macula causing significant visual loss
  • 5-6 mm round area centred on the fovea
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2
Q

what is the epidemiology of AMD?

A

. leading cause of irreversible visual impairment in the wester world
. responsible for 54% severe sight loss ( better eye worse than 6/60) in caucasian individuals
. one of the leading causes of certified vision loss in England and wales
. significant visual impairment (binoc 6/18 or worse ) in 4% aged 75+

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3
Q

what is the main pathogenic factors involved in AMD?

A
  • oxidative stress is one of the main pathogenic factors involved in AMD?
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4
Q

how is AMD classified ?

A
  1. Dry
    - atrophic/non-neovascular
    - 90% diagnosed cases
  2. Wet
    - neovascular/exudative AMD
    - 10% diagnosed cases
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5
Q

what is the changes that you see in early Dry AMD?

A

. drusen> 63 um
. RPE hyper/hypo pigmentation
. RPE atrophy

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6
Q

what are the changes that you see in late/advanced dry AMD?

A

. geographic atrophy (GA)

. sharply demarcated area of atrophy

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7
Q

what do you happens with wet AMD?

A

. choroidal neovascularisation (CNV), scarring (disciform)
. macular oedema
. sub retinal fluid(SRF)
- serous detachment of neurosensory retina
. RPE detachment (PED) or tear
. haemorrhages ( sub, intra pr pre retinal)
. exudates
. also includes
- retinal angiomatous proliferation (RAP)
- polypoidal choroidal vasculopathy ( PCV)

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8
Q

what is another classification of AMD?

A
  • category 1-
    .No AMD
    .none or a few small drusen <63um
  • category 2
    . early AMD
    . multiple small drusen or few intermediate drusen (63-124 um) or RPE abnormalities
  • category 3
    . intermediate AMD
    . extensive intermediate drusen, and at least on large druse ( >125 um ) or GA not involving the centre of the fovea
  • category 4
    . advanced AMD
    . GA involving the fovea and/or or any of the features of neovascular AMD
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9
Q

what are the early stages - histopathology of dry AMD?

A
  1. Basal laminar deposits
    - lipid deposition in Bruch’s membrane
    - failure of RPE to process cell debris
    - used as histopathological marker for AMD
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10
Q

what are drusen ?

A

. 1st clinically visible sign in AMD is drusen
. extracellular deposits between RPE and Bruch’s membrane
. derived from immune mediated and metabolic processes in RPE, consist of lipofuscin, amyloid, complement factors
. age related, common in 60+

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11
Q

what is hard drusen ?

A

. discrete, homogeneous , eosinophilic nodular deposits lying between the RPE and the inner collagenous layer of Bruch membrane
-tend to be small

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12
Q

what are soft drusen ?

A

. non-homogeneous, eosinophilic deposits with ill-defined margins

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13
Q

what are clinical features to consider with drusen?

A
  1. size
    - small (hard) <63 um
    - intermediate 63-125um
    - large > 125 um
  2. hard(discrete), soft or confluent
  3. associated with pigmentary changes?
    - hypo- or hyper-pigmentation
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14
Q

what is confluent drusen ?

A
  • mixture of small, intermediate and large drusen

- some of the larger drusen start to merge and become confluent

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15
Q

what are pigment changes as result of dry AMD?

A
  • hyperpigmentation

- pigment clumping

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16
Q

what geographic atrophy ?

A
  • its a sign of late Dry AMD

- its loss of RPE cells , which allows unmasking of the choroidal blood vessels

17
Q

how to evaluate the risk of progression to wet AMD?

A

-what you are looking for is :
- large drusen:
one eye?: 1
both eyes?: 2
- pigment changes
one eye?: 1
- in both eyes?: 2

score:

0: 0.5%
1: 3%- risk
2: 12 %
3: 25%
4: 50%
- px with late AMD in 1 eye have about a 50% chance of developing advanced AMD in fellow eye within 5 year

18
Q

what is the pathogenesis of wet AMD?

A
  1. thickening of Bruch’s membrane
    - increase advance glycation and (AGEs) products
    - increase in lipids and exogenous proteins
  2. hydrophobic barrier between choroid and retina
  3. ischaemia
  4. release of vascular endothelial growth factor VEGF
  5. neovascularisation from choriocapillaris via breaks in Bruch’s membrane
19
Q

what happens to the new vessels in the pathogenesis of wet AMD?

A
  • new vessels from choroicapillaris penetrate RPE
  • situated beneath neurosensory retina
  • new vessels are thin and ‘ leaky’ = exudates present
  • sub-retinal haemorrhage
  • CNV - choroidal neovascular membrane
  • sub retinal fluid (SRF)
  • PED ( pigment epithelium detachment)
20
Q

what is pigment epithelium detachment (PED)?

A
  • PED = detachment of RPE from inner collagenous layer of Bruch’s membrane
  • serous PED - orange dome shaped elevation , clearly defined edges
  • fibrovascular PED - much more irregular
  • drusenooid PED- shallower, develop from confluent large drusen
21
Q

what is sub-retinal haemorrhage ?

A
  • when bleed continues into sub- retinal space

- the overlying blood vessels are still visible

22
Q

what is the prevalence of late AMD in uk?

A

. 2.4% in population > 50 yrs ( = 513,000 cases )
. 4.8% in population > 65 yrs
. 12.2% in population > 80 yrs

. number of people with late AMD predicted to rise to 680,000 by 2020

23
Q

what are the risk factors of AMD ?

A
  • increase in age
  • genetics
    . family history of AMD
  • smoking
    . 3x more likely
  • cataract
evidence to suggest :
. gender
. diet
. atheroscleosis
. oxidative damage 
. phototoxicity 
. inflammation
24
Q

what are the symptoms of dry AMD ?

A
  • report gradual loss in central vision
  • asymptomatic - tend to happen in one eye only - subtle
  • distortion noticed on Amsler but not spontaneously reported
  • sometimes Px reports distortion in later stages
25
Q

what are the symptoms of wet AMD?

A

. sudden decrease in central vision
. monocular
. distortion
. positive blur in the centre of the vision - lines appear wobbly and not straight

26
Q

what are the diagnostic tools in AMD?

A
  • BCVA - best corrected vision in both eyes
  • Amsler grid for looking signs of distortion
  • reading speed
  • micoperimetry - perimetry for the central area
  • fundus binocular (VOLK)
  • OCT
  • FAF - fundus autofluorescence
  • FA - fluorescein angiography
  • multifocal ERG ( research tool )
27
Q

what is the optometric management of dry AMD?

A 
. px information 
- reassurance
. low vision aids 
- high adds
. prevention advice
28
Q

what is the optometric management of wet AMD ?

A

. urgent referral if VA> 6/96
. VA< 6/96 not urgent referral
- advanced untreatable disease characterised by subretinal fibrosis and/or pigmentary changes

  • direct referral to specialist macular clinic
29
Q

what is the preventative measures of AMD?

A
  • stop smoking
  • anti-oxidant supplements
    . in Px with advanced AMD in 1 eye, risk of progression to advanced AMD reduced by 25%
    .e.g macular carotenoids
  • diet
  • treatment of risk factors ( e.g. macular surgery)
30
Q

what is the ophthalmic management of AMD?

A
  • diagnosis
    . fundus BIO + OCT + FA
  • intra-vitreal anti-VEGF injections
  • surgery
    . laser
    . photodynamic therapy ( PDT)
  • low vision assessment
  • referral to ECLO
  • SI/SSI registration - sight impaired or severely sight impaired
31
Q

what are treatments for AMD in the future ?

A
  • macular translocation
    . lens implant that enhances central vision
  • phase 2 clinical trail for treatment of dry AMD
    . lampalizumab ( anti-factor D)
  • stem cell therapy

0V2022 Introduction to eye diseases (22 decks)

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