Glaucoma

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Glaucoma

• Visual Field Examinations
• Week 5

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Glaucoma

• Glaucoma is a disease of the optic nerve.
• Progressive loss of axon or nerve fibers cause
  irreversible visual field loss.
• The area of visual field loss is determined by
  where the damage has occurred either on the rim
  of the optic nerve or the nerve fiber layer.

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glaucoma
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High tension glaucoma

• Pressure readings higher than the normal, 10-21mm
  hg will be observed.
• The higher than normal pressure readings will
  cause a loss of axons throughout the nerve with
  concentric enlarging of the cup and thinning of
  the rim.
• This type of damage causes a generalized decrease
  in sensitivity.
• This type of VF loss is seen in the early stages
  of glaucoma.

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High tension glaucoma

• When viewing a VF automated printout, readings
  for the average normal VF should be in the
  lowers 30s centrally and upper 20s-lowers 30s
  in the peripheral VF.
• A patient with high tension glaucoma will have
  lower than normal readings across the whole VF.
• Progressively, the high tension patient will
  have a ring around the collar effect.
• This "collar will get progressively worse over
  the years and close in to tunnel vision and end
  stage glaucoma.

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High tension glaucoma

• This is an example of high tension glaucoma shown
  over a period of years.
• A computer printout from the Humphrey VF allows
  the technician to printout a comparison of all
  VFs done a one patient.
• This allows the doctor to see all of the VFs
  done on a patient so he doesnt have to flip
  through the chart to get the comparison.

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Low tension glaucoma

• Patients with low tension glaucoma will have
  pressure readings within the normal limits of
  mm hg.( between 10-21mm Hg)
• The damage from low tension glaucoma may occur in
  a more focal manner, with enlargement of the cup
  toward the superior and/or inferior poles of the
  disc.
• This will result in nerve fiber bundle defects in
  the VF.

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Low tension glaucoma

• Important note

• Redmacula
• Pinkdefect

• Nerve fiber bundle defects will always show
  opposite of the damaged area on the visual field.
• If the defect is on the inferior retina, it will
  show superior on the VF.

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Nerve fiber bundle defects

• Arcuate

• Arcuate

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Arcuate nerve fiber bundle defect

• This nerve fiber layer has damage inferiorly but
  shows superiorly on the VF.
• This reversal will always happen with any
  defect before the chiasm.
• Any defect in the retina, macula, and nerve will
  show opposite of the damage on the VF.

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Nerve fiber bundle defects

• Nasal step

• Nasal step

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Nerve fiber bundle defects

• Temporal wedge

• Temporal wedge

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Advanced glaucoma

• After years of glaucoma, the individual defects
  get worse.
• New nerve fiber bundle defects can occur and
  worsen.
• In advanced glaucoma or end stage glaucoma all of
  the individual nerve fiber bundle defects start
  to combine into one large defect, resulting in
  tunnel vision.

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Advanced glaucoma
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Lets see if youve been paying attention!
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Try this one!
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Last one!