Low Vision Techniques

Question 1

what is the set of guidelines called that outline the respectful way to interact with a patient who is visually impaired or blind

Answer 1

sighted guide

Question 2

what are the first 2 steps in sighted guide

Answer 2

ask patient if they need assistance and then make contact with their arm

Question 3

what is your arm position in sighted guide

Answer 3

relaxed by your side- bend elbow for patients who are unstable or frail

Question 4

what is your body position in sighted guide

Answer 4

the patient is a half-step behind you- they follow the movements of your body

Question 5

what are you telling the patient in sighted guide

Answer 5

providing verbal cues about environment, location, direction traveling, inform what is in rooms and if there are people in the room

Question 6

what do you do in sighted guide while going through a door, narrow space or crowd

Answer 6

move your arm behind back and position yourself to open the door with your free hand

Question 7

what is the sighted guide procedure for stairs

Answer 7

alert the patient when you approach stairs, say up or down, inform them where the hand rail is and tell them when the last step is coming

Question 8

what are the steps to taking a distance VA

Answer 8

reduce test distance, hand motion (record distance), light projection and light perception *Do not do count fingers!

Question 9

which chart method is in meters

Answer 9

ETDRS

Question 10

what chart method is in feet

Answer 10

Feinbloom

Question 11

what chart is the gold standard in low vision

Answer 11

ETDRS (also used in research)

Question 12

what are some advantages of an ETDRS chart

Answer 12

improves standardization and accuracy in measuring VA, same number of optotypes per row, equal spacing and uses log scale, variable test distance, equal optotype difficulty, and high contrast optotypes

Question 13

what are some benefits of the Feinbloom chart

Answer 13

portable, test at any distance, high contrast numbers, large optotypes, can measure less than 20/800

Question 14

what are 2 disadvantages of the Feinbloom chart

Answer 14

variable number of optotypes per page and variable spacing between optotypes

Question 15

what is M notation used for

Answer 15

metric system for measuring VA in vision rehabilitation distance and near testing

Question 16

what is the starting distance for ETDRS

Answer 16

2m (can move to 1m if needed) - easy conversion to 20 feet

Question 17

what is the starting distance for Feinbloom

Answer 17

10 feet (move closer if needed 5, 4, 2, 1 feet)- multiple of 20 for easy conversion

Question 18

which chart is useful for eccentric viewing testing

Answer 18

Feinbloom

Question 19

when can you not use reduced snellen near VA

Answer 19

if test distance is different than 40cm

Question 20

what is the equation to convert to snellen equivalent

Answer 20

VA= test distance / letter size and cross multiply and divide by acuity (2/16=20/x –> x=160)

Question 21

how can you do the snellen conversion in your head

Answer 21

when testing at 2 meters- multiply both numerator and denominator by 10 (if 1 meter multiply by 20)

Question 22

what is point notation

Answer 22

based on typography (computers)- measures the size of typeface or the height of the letter

Question 23

what is the conversion triangle for snellen - point - meters

Answer 23

Snellen –(Divide by 6)→ Point –(divide by 8)→ Meters –(multiply by 50)→ Snellen

Question 24

what is JND

Answer 24

just noticeable difference - minimum lens change that a patient can appreciate during a trial lens refraction

Question 25

what does JND equal

Answer 25

the denominator of equivalent snellen VA (move decimal place to 1/100 position) units are diopters

Question 26

what loose lens do you choose for a trial frame refraction

Answer 26

+/- JND/2

Question 27

You have the ETDRS chart at 1 meter and the patient reads the 8 M line. How do you record the visual acuity?

Answer 27

1M/8 (20/160)

Question 28

Kathy read all of the letters on the 15M line when you placed the chart at 2 meters away from her. How do you properly record her visual acuity?

Answer 28

2M/15 (20/150)

Question 29

You use the Feinbloom chart at 10 feet and the patient reads the 150 foot line. How do you record the visual acuity?

Answer 29

10ft/150 (20/300)

Question 30

how do you record near VA in low vision

Answer 30

record exact test distance and actual letter size - measure near VA at patient's preferred working distance (record in METERS)

Question 31

how would you record if a patient read 1.6M letter size at 20cm

Answer 31

0.20/1.6M

Question 32

Karen is wearing her glasses. The chart is held at 20 cm, The patient reads to 1.25 M with both eyes open. how would you record near VA

Answer 32

OU cc 0.20/1.25M (20/125)

Question 33

Stacey needs to read 6 point type bank statements while working at a financial institution. What is the M-Unit?

Answer 33

0.75M

Question 34

During the vision rehabilitation examination, Josh was able to read the 1.25M letter size on the Lighthouse near acuity chart. What is the equivalent point type that he’ll need to use on his computer in order to see it?

Answer 34

10 point

Question 35

OD 2M/16 (20/160) OS 2M/25 (20/250) What is the OD JND?

Answer 35

1.60D

Question 36

OD 2M/16 (20/160) OS 2M/25 (20/250) What are the loose lenses you will select to produce JND for OD?

Answer 36

1.00D

Question 37

OD 5ft/120 (20/480) OS 5ft/240 (20/960) What is the JND for OD?

Answer 37

4.80D

Question 38

how do you determine the distance magnification needed

Answer 38

denominator of actual VA/ denominator of goal VA

Question 38

what is distance magnification specified in terms as

Answer 38

angular magnification with unit "x"

Question 38

what is the purpose of predicting magnification

Answer 38

determine the starring power of optical devices

Question 38

what is the formula we will use for predicting near magnification

Answer 38

Equivalent viewing distance

Question 38

what is angular magnification

Answer 38

using an optical system to increase the angular subtense of the image compared to the angular subtense of the object itself

Question 38

OD 2M/25 (20/250) OS 2M/8 (20/80) and goal VA 2M/4 (20/40) for driving- what is distance magnification for OD and OS

Answer 38

``` 25/4 = 6.25x 8/4 = 2x ```

Question 38

what is the equivalent viewing distance (EVD) formula

Answer 38

(actual near VA denominator/goal near VA) x (accommodative demand or reference add power)

Question 38

OD 0.20M/2.5, OS 0.20M/3.2, reference add used +5 D Goal VA for reading large print fiction books 1.6M what is the near magnification needed

Answer 38

OD: 2.5M/1.6M x +5D = +7.8D OS: 3.2M/1.6M x +5D = +10D

Question 38

if a patient need +12D near magnification, what is the working distance going to be?

Answer 38

8cm --> focal distance of 12D lens = 1/12

Question 38

what are 5 categories of optical devices

Answer 38

near, intermediate, distance, adaptive/assistive technologies and non-optical

Question 39

what are some examples of near optical devices

Answer 39

specs: high +, microscopic lenses, base-in prisms, doublet lenses, hand or stand magnifiers, and reading telescopes

Question 40

what are 2 examples of intermediate optical devices

Answer 40

loupes and telescopes

Question 41

what are some distance optical devices

Answer 41

monocular telescopes, spec mounted telescopes, and binocular telescopes

Question 42

what are some adaptive/assistive technologies for optical devices

Answer 42

desktop CCTV, computer software programs, OCR technology, GPS navigation systems

Question 43

what are some non-optical devices

Answer 43

absorptive filters (sunglasses), fitover sunglasses, typoscope, liquid level indicator, lamps, felt tip pens, talking watch/clock, dots

Question 44

what is the california central visual field test

Answer 44

several laser brightness intensities to allow for more sensitivity in plotting clinically significant scotomas