Packet 1: low vision rehabilitation

Question 1

most common cause of low vision in the US is

Answer 1

macular degeneration

Question 2

1 reason for hereditary vision loss is

Answer 2

retinitis pigmentosa

Question 3

the definition of legal blindness in the US is based off what categories

Answer 3

visual acuity and visual fields

Question 4

definition of legal blindness in the US is

Answer 4

• 20/200 or less in better seeing eye, best corrected

- less than 20 degrees of visual field in better eye

Question 5

what does legal blindness definition NOT account for for other types of vision loss

Answer 5

• decreased contrast sensitivity
• visual distortion
• glare disability
• ocular motility deficits

Question 6

do you have to be legally blind to have low vision?

Answer 6

no

Question 7

what is low vision but not legally blind definition usually

Answer 7

20/70 or worse in the best eye based on most insurance criteria and medicare

Question 8

ICD10 code “0”: mild or no visual impairment

Answer 8

equal to or better than 20/70

Question 9

ICD10 code “1”: moderate visual impairment

Answer 9

• worse than 20/70

- equal or better than 20/200

Question 10

ICD10 code “2”, severe visual impairment

Answer 10

• worse than 20/200

- equal or better than 20/400

Question 11

ICD10 code “3”: blindness

Answer 11

• worse than 20/400

- equal or better than 20/1200

Question 12

ICD10 code “4”: blindness

Answer 12

• worse than 20/1200

- equal to or better than light perception

Question 13

ICD10 code “5”: blindness

Answer 13

no light perception

Question 14

what is “any loss or abnormality of psychological, physiological, or anatomical structure or function”

Answer 14

impairment

Question 15

what is “any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being”

Answer 15

disability

Question 16

does a visual impairment always cause a visual disability?

Answer 16

no

Question 17

overview of case history in low vision

Answer 17

• chief complaint
• near needs/ abilities
• distance needs/abilities
• activities of daily living issues
• social history
• illumination and glare needs
• mobility needs
• job related needs

Question 18

what is light projection (vs. light perception)

Answer 18

light projection= direction of light (better than LP only)

Question 19

3 most common charts used in low vision

Answer 19

• Snellen
• EDTRS/ Bailey Lovie
• Feinbloom

Question 20

what are some problems with using Snellen charts?

Answer 20

• may not have enough lines
• not enough characters per line (more so for higher acuity loss)
• projector charts may vary in contrast as background illumination changes

Question 21

why is Bailey Lovie/EDTRS charts considered the Gold Standard?

Answer 21

• 5 letters in each row
• standardized spacing between letters and rows
• progression of letter sizes constant and follows log scale (log MAR)
• every 3 lines down on chart represents a change in acuity of 1/2

Question 22

what is the highest level of acuity in Bailey Lovie/ETDRS

Answer 22

10/125

Question 23

if patient has worse than 10/125, what do you do?

Answer 23

use Feinbloom chart or move in to 5 feet

Question 24

pros/cons of Feinbloom chart

Answer 24

pros: numbers, portable, large type (700ft), generous spacing
cons: limited number of optotypes, psychological advantage (can guess)

Question 25

what are some special things to include when you record low vision acuity

Answer 25

- type of chart used - no + or - notation - test distance where measured (so 10ft usually) - note illumination conditions during testing - style and efficiency of how patient read chart

Question 26

what chart should you use if patient has central scotoma and has poor eccentric viewing skills

Answer 26

feinbloom chart with single optotype may be easiest

Question 27

what strategy should you use to measure VA on a patient with overall reduced visual field?

Answer 27

``` start smaller (because larger optotypes may be out os patients field and unable to be fully viewed) ```

Question 28

what are 4 ways to notate near visual acuity

Answer 28

- Jaeger - Reduced Snellen (RS) - Point size - M units

Question 29

what are some cons of Jaeger notation

Answer 29

- style and size vary from chart to chart - no constant ratio between type sizes (not easily converted to standard notation) - least useful of all the resting methods

Question 30

pros/cons of reduced snellen

Answer 30

- same notion as distance snellen | - but reduced snellen assumes testing distance at 40cm so if any other distance, confusion begins

Question 31

what is point size or N way of measuring near acuity

Answer 31

- used by school teachers, librarians, printers - refers to the size of the printing press letters are set in - not an exact system of recording VA (no good)

Question 32

what is the "N system" way of recording near acuity

Answer 32

"British N" - variety of point size notation using Times Roman - ex: N16 at 30cm

Question 33

the gold standard for near acuity is

Answer 33

Metric (M) notation

Question 34

how is metric (M) notation work and how is it recorded

Answer 34

- standardized for test distance of 1 meter - M notation is linear (follows logMAR) - record test distance in meters over M size

Question 35

types of near vision charts that can be used

Answer 35

- lighthouse cards (used the most) - reduced snellen (bad) - SK read - MN read

Question 36

what are some unique things about SK read (Smith-Kettlewell reading test)?

Answer 36

- determines critical print size, magnification requirements, scooters interfering with reading - can be used as a training tool to promote awareness of scotoma location

Question 37

what are some unique things about MN read (minnesota low vision reading acuity charts)

Answer 37

-used to assess how reading performance depends on print size (max reading speed, critical print size, reading acuity)

Question 38

what can you use to plot a person's contrast sensitivity function?

Answer 38

detailed contrast sensitivity measurements that include both size (spatial frequency) and contrast

Question 39

your CSF is essential a plotting of the curve that defines the:

Answer 39

lowest contrast sensitivity level you can detect for each spatial (size) frequency tested

Question 40

what spatial frequencies must have significantly higher contrast to be detected by the human visual system?

Answer 40

higher spatial frequencies (sine-wave gratings with very thin bars)

Question 41

normal contrast sensitivity function is ___%

Answer 41

2-3%

Question 42

at 2.5-5% CS function, patient would have difficulty with:

Answer 42

determining facial expressions, recognizing friends, detecting curbs and drop offs

Question 43

at 10% CS function, patient would have difficulty with:

Answer 43

detecting changes in surfaces, black and white photographs, water on the floor

Question 44

at 25% CS function, patient would have difficulty with:

Answer 44

safe mobility, night driving

Question 45

what is considered a functional impact of contrast acuity?

Answer 45

greater than 2 line loss on low contrast acuities