Visual fields Flashcards
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)
