Age related macular degeneration (AMD)

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  • Created by: z
  • Created on: 13-03-16 18:03

AMD

  • gradual loss of central vision 
    • may be v slow, over years or sudden deterioration if assoc w/ haemorrhage
  • first symptom ususlaly distortion
  • eventual severe loss of central vision but maintain peripheral vision
  • difficulty w/ reading, recognising faces
  • use Amsler chart
    • square grid, one eye at  a time, mark any distortions on chart
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AMD

  • gradual loss of central vision 
    • may be v slow, over years or sudden deterioration if assoc w/ haemorrhage
  • first symptom ususlaly distortion
  • eventual severe loss of central vision but maintain peripheral vision
  • difficulty w/ reading, recognising faces
  • use Amsler chart
    • square grid, one eye at  a time, mark any distortions on chart
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Dry AMD

  • geographic atrophic causing severe central vision loss
  • accounts for 90% of AMD
  • no Rx that can halt or reverse the progression
  • precursor lesion that leads to geographical atrophy is a small yellowish macular lesion called 'drusen' of which there are 2 types- soft or hard
    • soft drusen: pale yellow, large, ill-defined margins- sign of AMD if >63 microns and pt >55yrs, evolve to macular degeneration
    • hard drusen: round, yellow, well definied margins- relatively common not always assoc. w/ AMD
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Wet AMD

  • less common but more severe
    • 10% of AMD but 90% of blindness from AMD
  • characterised by choroidal neovascularisation (CNV)
    • CNV: the development of abnormal blood vessels beneath retinal pigment epithelium (RPE) layer of the retina
    • identified on funduc flouroscein angiography
    • new bvs penetrate into the macula region and bleed
    • this causes macula scarring (disciform scar) which causes loss of central vision
  • most eyes with AMD due to CNV udner the fovea are legally blnd w/in 2 yrs of diagnosis
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Progression of AMD + risk factors

  • Drusen evolve from hard to soft, incr in size, number and confluence - evolve to dry or wet macular degeneration
  • 5 yr risk of pt >80yrs w/ soft drusen is 42%
  • if AMD in one eye, risk of fellow eye developing AMD is 39-55%
  • progression:
    • no maculopathy + hard drusen > soft drusen +/- pigment changes > geographic atrophy/CNV + disciform scar
  • risk factors:
    • age
    • smoking 
    • FHx
    • complement factor H gene (CFH)
    • possible RFS:
      • sunlight
      • CV: high BP, high chol, obesity
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AMD treatment

  • dry
    • no Rx
    • magnifiers for reading
    • vitamins- if advance AMD in one eye to prevent deterioration in other eye- high dose zinc and antioxidant vitamins (vit C, vit E, beta-carotene)
    • severely sight impaired/sight impaired registration
    • social support
  • wet
    • previously- verteporfin
    • ranibizumab, bevacizumab (avastin)
      • non-selective VEGF-A inhibitors
      • b/c VEGF-A implicated in bv growth and leakage, involved in CNV
      • intravetreal injections, either in clean room or theatre- risk of endophthalamitis
      • 2 year course can stabilise condition and sometimes restore vision
    • aflibercept
      • soluble VEGF receptor fusion proteins- binds all forms of VEGFA,B
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