Observation and Testing for Vision Impairment

Question 1

What are the 3 main types of vision?

Answer 1

Photopic vision
Mesopic vision
Scotopic vision

Question 2

What is photopic vision? 3

Answer 2

-Cone photoreceptors/color vision
-Resolves fine detail 20/20 or better: high acuity
-Functions only in good illumination

Question 3

What is Mesopic vision? 3

Answer 3

-Both rods and cones function over a wide range of light at simultaneous levels
-Intermediate levels of chromatic function
simultaneously.
-Twilight or dusk occurs in a mixed rod/cone mode

Question 4

What is scotopic vision? 5

Answer 4

-Uses rod photoreceptors
-Occurs in very low light levels
-Exhibits poorer quality vision
-Is limited by resolution (usually 20/200 or less) for acuity
-Provides ability to discriminate only shades of black and white

Question 5

When going from day to night what types of vision are being used? 3

Answer 5

photopic to mesopic to scoptic vision

Question 6

What vision type is happening when their is no significant light source?

Answer 6

Pure scotopic vision

Question 7

Are rods or cones more sensitive at lower levels of light?

Answer 7

rods

Question 8

What are the parameters of ocular functions? 6

Answer 8

-Macula function
-Provides binocular vision
-Visual acuity (VA) better than 20/200
-Central vision less than 10 degrees
-Stereopsis
-Color vision

Question 9

What basic visual function test are included in the Activities of Daily Living (ADL)? 5

Answer 9

-Acuity test
-Stereopisis
-Color Perception
-Visual Field
-Muscle balance

Question 10

What does an acuity test check? 3

Answer 10

-Monocular and binocular vision
-Both distance and near visual acuity
-With and without correction

Question 11

Why do we perform visual screenings? 2

Answer 11

1. Analyze anatomic and structural changes caused by disease or
   injury.
2. To find relationship of these functional changes to the visual
   requirements of (ADL) or specific
   occupational requirements

Question 12

What are the reasons for the specific types of vision testing? 4

Answer 12

1. Functional Vision
2. Binocular Vision
3. Monocular Vision
4. Contrast Sensitivity

Question 13

What does functional testing check for? 3

Answer 13

-how the eyes and the visual system function
-If organ functions are reduced, they are referred to as
impairments
-Cerebral vision impairments may cause abnormal vision

Question 14

How does binocular vision help us? 3

Answer 14

-Makes hard-to-see objects easier to detect,
-Enlarges the total field of view
-Improves a person’s capacity to distinguish small
differences in depth.

Question 15

If organ function is reduced what is it refferred to as?

Answer 15

an impairment

Question 16

If someone only uses monocular vision what condition could they be suffering with? 5

Answer 16

-Suppression
-Amblyopia
-Tropia
-Disease
-Trauma

Question 17

What does contrast sensitivity test for?

Answer 17

Determines the lowest contrast level that can be detected by a person for a given size target

Question 18

What is one of the most common tests for contrast sensitvity?

Answer 18

Pelli-Robson

Question 19

What does the Pelli-Robson use in the test to check for contrast sensitivity?

Answer 19

Uses letters with sharp edges that are more like actual objects.

Question 20

What is the standard test for visual acuity?

Answer 20

Snellen Chart

Question 21

what does the snellen chart measure for?

Answer 21

resolution of fine detail at
high contrast.

Question 22

what does stereopsis measure for?

Answer 22

depth perception with book and 3D glasses

Question 23

what is the colour perception test called?

Answer 23

ishihara’s test

Question 24

In what situation other than someone being colour blind could they fail the color test?

Answer 24

low visual acuity (20/50 or less)

Question 25

Review interventions for rehabilation.