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Methods Block 2 > Visual fields > Flashcards

Flashcards in Visual fields Deck (17)
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1
Q

Visual field

A
  • the entire area that can be seen when the eue is directed forward, including peripheral vision.
  • entire expanse of space visible at a given instant without moving the eyes(field of vision)
2
Q

How is visual field different from VA?

A
  • VA is spacial resolution and you’re looking right at the object
  • this is all image space
3
Q

Visual field test

A

-a test that measure the extend and distribution of the field of vision

4
Q

Why do VF testing?

A
  • many diseases associated with VF(glaucoma,strokes,tumors(identify location and type based on VF)
  • medication toxicity
  • occupational standards
  • determine functional loss(benefits for vision loss, cosmetic coverage)
5
Q

Horizontal vs vertical

A

-usually test horizontal, but with droopy lid/cosmetic surgery, test vertical

6
Q

Visual field screening

A
  • generally done when VF loss unlikely, but possible
  • will miss subtle things, but get gross defects
  • quick and easy screening
7
Q

Qualitative/ diagnostic field testing

A
  • determine the characteristics of VF defect
  • location, borders, shape, size
  • quality of VF
8
Q

Quantitative VF testing

A
  • fully quantifies a known or suspected defect so future changes are detectable
  • requires automated threshold perimetry
  • tests level of sensitivity
  • measures it numerically
9
Q

Incidence of VF lost

A

3-5%
10-15% in ages 65 and up

-4.4% of those appearing for their first eye exam had VF defects and in HALF, the cause was SIGHT OR LIFE THREATENING (20-25 patients)

10
Q

Symptoms

A
  • defects are often asymptomatic and may be the only detectable evidence of a disease/disorder
  • patient probs isnt going to notice
11
Q

Confrontation VF

A
  • can be done multiple ways
  • simple screen for gross VF loss
  • sensitivity not very high
  • better for posterior visual pathway legions than anterior pathway legions
12
Q

basic techniques for confrontation

A
  • sit about a meter away
  • ONE EYE AT A TIME
  • they cover left, you cover right
  • comparing their VF to yours
  • NO GLASSES CL doesnt matter
  • make sure patient keeps fixation and you test all quads
  • dont favor your space or theirs, keep it in the middle
  • make sure target it fully in one quad
  • dont make it too hard or too easy
13
Q

Central VF

A
  • usually BUT NOT ALWAYS associated with reduced VA
  • i.e patient can probably tell
  • not routinely screened for
  • screened when macular problems are suspected
14
Q

Amsler grid testing

A
  • quick way to check for gross defects
  • central 10 degrees of VF
  • qualitative assessment of macular function
  • may be given to patients to monitor at home
15
Q

Scotoma

A

-defect within a field of vision

16
Q

Normal Amsler grid results

A
  • dot at center seen when looking directly at it
  • all four corners seen when looking at dot
  • no areas of grid missing
  • no grid distortions
17
Q

Normal VF results

A
  • full in extent(up down side side) for both eyes
  • free of blind spots(scotoma)
  • free of areas of distortion(metamorphopsia)