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3F: Low Vision > Special Testing > Flashcards

Special Testing Flashcards

1
Q

Reasons for testing VF in low vision

A

Determine functional impairment
Determine legal blindness
Correlate with pathology

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2
Q

Automated VF

A
  • advantage of standardization and is easier to use
  • can be used to determine legal blindness (MD greater than 22DB)
  • has both static and kinetic automated programs
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3
Q

Arc perimetry

A
  • the VF can also be tested using a hand perimeter

- came with various target sizes, generally uses 3mm first and increases the target to 5mm if the patient struggles

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4
Q

Arc perimetry instruction

A
  1. Cover OS, habe the patient hold instrument horizaontal and place against the patients nose
  2. Position the OD a few inches above the center dot and tell the patient to fixate on the central target
  3. The wand is held just temporal to the fixation point, the patient is asked if he or she can hold fixation o the central target whilst seeing th peripheral target. Can also ask if patient is able to see two dots, including the one you are moving and the one on the disc
  4. The wand is moved outward gradually and the patient is instructed to report when the moving target disappears. If it disappears within appx 15 degrees, the patient is reassured that this area is the normal physiological blind spot. If the examiner suspects malingering, occasionally turn the wand around during testing so that the target disappears. If the patient still claims to see the target while it is turned, the malingering is confirmed
  5. continue to test in clockwise pattern in order to maintain a systematic order
  6. If the patient has poor response to the smaller target increase
  7. Switch eyes and repeat until all 8 meridian ends rate eval
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5
Q

Arc perimetry norms

A

For a 3mm target at 13 inches (the typical target at the distance of the radius of the perimeter), the normal findings are as follows

  • 90 degrees or more temporally
  • 55 degree superiority
  • 60 degrees nasally
  • 70 degrees downward

Norms are demonstrated on the official recording form by the shaded areas

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6
Q

Arc perimetry recordings

A
  • the limits of the field can change based on the level of illumination in the room-make sure tour room is adequately lit
  • for patients that have difficult with speaking, you may have to move your target mroe slowly or use shorter phrases)
  • make sure that the disc remains at the meridian you are testing and that you do not accidentally turn your target away from your patient during testing
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7
Q

Conventional perimetry

A
  • allows quantification of the visual field

- accuracy is based on two assumptions

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8
Q

Accuracy of conventional perimetry is based on these two assumptions

A

Fixation is stable

Fixation is located at he fovea

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9
Q

What is conventional perimetry not good for

A

Precise evaluation of macular disorders

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10
Q

Microperimetry

A
  • minomer: night stimulus size nor test grid are “micro”
  • refers to perimetry when there is real time visualization of the fundus
  • first used by Timberlake over 20 years ago
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11
Q

Microperimetry and scotomas

A

Determination of scotomas

  • size
  • location
  • relative vs absolute
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12
Q

What can microperimety determine

A

Scotomas and fixation

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13
Q

How can microperimetry determine fixation

A

Location
Stability
Development of preferred retinal locus (PRL)

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14
Q

Preferred retinal focus

A

Retinal area that behaves as a pseudofovea and is adopted by the patient to see chosen object

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15
Q

NIDEK MP1

A
  • is NOT and SLO
  • infrared fundus camera 45 degree FOV
  • automated eye tracking
  • automated static threshold or customized using liquid display
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16
Q

Spectral OCT/SLO

A

A tool used with microperimetry that can show retinal damage in certain diseases

17
Q

Macualr integrity assessment (MAIA)

A
  • linear SLO system and fundus controlled perimetric exam
  • limited ability to adjust parameters
  • can adjust stimuli locations
18
Q

MAIA useful for

A

Rehabilitation recommendations
Patient and family education
Making sense out of patient complaints

19
Q

Location of PRL and reading speeds (fletcher)

A

Not strongly associated with reading speeds

20
Q

PRL and reading speeds today

A
  • PRL training using a microperimeter like the MAIA can be very successful and improve reading time
  • groups trained in two different methods to adopt a more efficient retinal locus improved the median reading speed by 20-21 wpm
  • when reading a 2000 word newspaper page, a reading speed of 83 wpm would require 24 minutes. When increased by 21 wpm to 104 wpm, it would require 19m, which saves 5 minutes
21
Q

Amsler grid testing

A
  • patients may report normal even in the present of large macular scars
  • nearly half of scotomas are missed by the amsler grid
  • AG underestimates extent of scotomas
  • 65% of patients placed their PRL on the center of the grid, giving the illusion of a paracentral scotoma when in fact it was central
22
Q

Facial amsler

A
  • have patient view your face looking right at your nose. Which part of your face is the most clear?
  • sunless found facial fields to be accurate to microperimetry results in 74% of cases. In clinics with not access to a microperimeter, facial amsler is quick and recommended
  • you can hold your hand at different places around your face and ask the patient to look at your hand. At which place is your face the most clear in their peripheral vision?
23
Q

Home exercises for training locus

A
  • place an object near their TV in the appropriate location that they should look at when watching TV
  • use large print playing cards
  • with hand held steady, patient presents the playing cards directly in front of themselves. They turn only their eyes to the appropriate EV point to identify the card. Go through the deck 3x daily. Once able to do this easily, move on to pre-reading exercises.
24
Q

Pre-reading and reading exercises

A
  • often trained by occupational therapists

- more about this later in the course

25
Q

SLO and anti-VEGF

A
  • always find scotomas in pre anti-VEGF eyes with wet AMD

- avastin appears to reduce size and depth of scotomas

26
Q

Colorvision

A
  • the main test used for testing color vision in low vision is the large D-15, also referred to as Panel 16
  • in low vision clinic, the patients conditions are already diagnosed, so colro visio testing is generally performed binocularly
  • educate pateitn well so that they understand the test
27
Q

Mars letter contrast sensitivity test

A
  • set of 3 near charts
  • each letter fades by 0.04 log units
  • have the patient read the chart until they read two consecutive incorrect responses

Pelli-Robson uses triplets
-each triplet fades 0.08 log units

28
Q

Profound vision loss on mars letter contrast sensitivity

A

<0.048

29
Q

Severe vision loss on mars letter contrast sensitivity

A

0.52-1.00

30
Q

Moderate vision loss and mars letter contrast sensitivity

A

1.04-1.48

31
Q

Normal vision loss in > age 60 mars letter contrast sensitivity test

A

1.52-1.76

32
Q

Normal < 60 age vision loss and mars letter contrast sensitivity

A

1.72-1.92

33
Q

Other contrast tests

A

Pelli Robson

iPad HOTV

3F: Low Vision (16 decks)

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