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PPO 2 > Low vision techniques > Flashcards

Low vision techniques Flashcards

1
Q

What are the differences in vision rehab exam and general eye exam

A
  1. detailed functional case history
  2. obtain VA differently
  3. trial frame refraction
  4. central field test
  5. contrast sensitivity
  6. optical device testing
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2
Q

What do you do if the patient fails to read even the largest target

A
  1. Reduce the test distance
  2. wiggle your hand
  3. use a light and ask where?
  4. use a light and ask, can you see it turn on or off. If patient cant determine if room lights are on or off –> no light perception
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3
Q

WHat are the benefits of a standard projector chart

A
  1. doesnt require room lighting

2. lines can be isolated

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4
Q

What are the disadvantages of a standard projector chart

A
  1. poor measurement of <20/100 vision
  2. no uniform spacing and amount of letters per line
  3. set distance
  4. variable contrast and illumination
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5
Q

What are the benefits of a computerized acuity system

A
  1. many choices of optotypes
  2. eleminates patient memorization
  3. high contrast optotypes
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6
Q

What are the disadvantages of computerized acuity systems

A
  1. poor measurement of <20/100 vision
  2. less optotypes per line
  3. Set test distance
  4. limited by size of screen.
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7
Q

Why is the ETDRS chart the most benefiical

A
  1. Same number of optotypes per row
  2. equal spacing of optotypes and rows on a log scale
  3. variable test distance
  4. equal optotype difficulty
  5. high contrast optotypes
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8
Q

What are the benefits of a feinbloom chart (handheld)

A
  1. portable
  2. test at any distance
  3. high contrast numbers
  4. large optotypes
  5. can measure <20/800
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9
Q

What are the disadvantages of a feinbloom chart

A
  1. variable number of optotypes per page

2. variable spacing between optotypes

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10
Q

ETDRS chart measures VA in ____whereas, feinbloom measures in ______

A

meters; feet

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11
Q

Recording Distance VA

A
  1. Always record the exact test distance you used and actual letter size
  2. extrapolations are noted in parenthesis (20 feet equiv)
  3. note the chart you used
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12
Q

Why do we record VA diff in vision reha

A
  1. more accurate measure of visual acuities = can alter test distance and can obtain VA for severe to profound vision loss
  2. can repeat the same testing conditions as the previous clinician
  3. easily determine if any changes in VA
  4. avoids confusion about which testing conditions were used
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13
Q

Near VA is recorded in ___units NOT reduced snellen

A

meter

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14
Q

1M = ____ min arc @ 1 meter

A

5

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15
Q

To go from snellen to point notation you would ____by ____:

A

divide; 6

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16
Q

To go from point to meters you would ____ by ____

A

divide; 8

17
Q

To go from meters to snellen you would ____ by ____

A

multiply; 50

18
Q

What is spot acuity

A

Limit of acuity to be able to recognize print; quick reading

19
Q

What is sustained reading acuity

A

limit of acuity for reading print for a longer period of time (~10 mins or more); ex reading books, mags, or newspapers

20
Q

What is the static visual field testing for

A

peripheral field; stimulus changes in brightness; techniques are confrontation field, humprey automated perimetry, and octopus perimetry

21
Q

what is the kinetic visual field testing for

A

points tested are moving from an unseen area to a seeing area. stimulus brightness is the same; techniques include tangent screen, humphrey SSA kinetic test, goldmann perimetry, octopus perimetry

22
Q

central field tests:

A

asses the central 20-30 degrees of the visual field; techniques include the amsler grid, humphrey automated perimetry, california central visual field test, octopus perimetry

23
Q

What is the California Central Visual Field Test

A

Several laser brightness intensities allow for more sensitivity in plotting clinically significant scotomas. Examiner views patients fixation and eye movements better. Can be done monocularly and binoclularly

24
Q

What is the test distance for CCVFT and what does 1 cm = to

A

57 cm. 1 cm= 1 degree

25
Q

What is the SK designed for

A

to allow words to be easily confused and fascilitate mistakes encountered while reading; pattern of mistakes differentiate left and right sided scotomas.

26
Q

Eye dominance does NOT correspond to ____dominance

A

hand; or better functioning eye

27
Q

Which eye conditions affect your ability to see contrast

A
  1. Optic nerve diseases
  2. age related macular degeneration
  3. cataracts
  4. diabetic retinopathy
28
Q

The Pelli-robson contrast sensitivity chart is the the gold standard because

A

contrast differes by every letter triplet. Quick and easy to administer, and you get reliable results. Test distance is at 1 meter.

29
Q

When does the pelli-robson test end

A

when 2 letters are missed within a triplet set

30
Q

What is the final log contrast sensitivity:

A

the last triplet where patient reads 2 letters within a triplet correctly

31
Q

WHat is the MARS contrast sensitivity chart

A
  1. its used for near…50 cm test distance
  2. differ in contrast with each letter
  3. measures peak contrast sensitivity, not plotting the entire contrast sensitivity curve
32
Q

What is JND

A

“just noticeable difference” for patient- the minimum lens change that a patient can appreciate. It is equal to denominator of eq Snellen VA and are measured in diopters

33
Q

What is the purpose of predicting magnification

A

To determine the starting power of optical devices used to demonstrate to the patient

34
Q

How do you calculate distance magnification needed

A

Denominator of actual VA/denominator of goal VA. Recorded in “X”

35
Q

How do you record near VA for magnification

A

in Diopters

36
Q

How do you find the near magnification for the kestenbaum formula

A

Reciprocal of distance vision

37
Q

How do you find the near vision for the lighthouse method

A

reciprocal of near vision x reference add

38
Q

What is the Equivalent viewing distance formula (EVD)

A

Actual near VA denominator/Goal near VA x reference add

this is the one most used in clinic

PPO 2 (4 decks)

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