Visual Ability & Physiology

Question 1

Visual impairment is the…

Answer 1

consequence of a functional loss of vision.

Question 2

eye disorders (9)

Answer 2

1. Retinal degeneration
2. Albinism
3. Cataracts*
4. Glaucoma*
5. Nystagmus
6. Corneal disorders
7. Diabetic retinopathy*
8. Congenital disorders
9. Infection

Question 3

monocular vision

Answer 3

perfect or nearly perfect in one eye, but little or none in the other

Question 4

visual acuity

Answer 4

ability to see objects clearly in distance (refractive index)

Question 5

low vision defined (2)

Answer 5

1. VA between 20/70 and 20/400
2. visual field 20 degrees or less

Question 6

blindness defined (2)

Answer 6

1. VA less than 20/400
2. visual field 10 degrees or less

Question 7

“legally blind” in US defined (2)

Answer 7

1. VA less than 20/400
2. visual field 20 degrees or less

Question 8

normal visual field range

Answer 8

70 degrees to left and 104 to right

Question 9

age-related macular degeneration (ARMD)

Answer 9

gradual loss in center due to vascular problems of choroid plexus

Question 10

visual icon non-speech cues (3)

Answer 10

1. Auditory icons (everyday sound)
2. Earcons (abstract sound)
3. Hearcons (nature/ music sounds)

Question 10

cataracts

Answer 10

clouding of the lens causing blurred vision

Question 11

diabetic retinopathy

Answer 11

changes to retina blood supply causing loss of visual field with random black areas (most common)

Question 12

long cane pros (3)

Answer 12

1. low cost
2. simple to use
3. well-developed training

Question 13

long cane cons (2)

Answer 13

1. only detects in front of user
2. not detect objects above waist

Question 14

Electronic Travel Aids parts (3)

Answer 14

1. environmental interface
2. information processor
3. user display

Question 15

What causes glaucoma?

Answer 15

increased pressure of aqueous humor damaging retinal cells

Question 16

Glaucoma is the second leading cause of blindness worldwide. (T or F)

Answer 16

True

Question 17

age-related macular degeneration types (2)

Answer 17

1. “dry” / atrophic (more common)
2. “wet” / endovascular

Question 18

retinitis pigmentosa

Answer 18

degeneration of the photoreceptor rods (narrow sight/ black around)

Question 19

Where is vision processed?

Answer 19

occipital lobe of brain in back of head

Question 20

correction of myopia (nearsighted)

Answer 20

concave lens (diverged)

Question 21

correction of hyperopia (farsighted)

Answer 21

convex lens (point focus)

Question 22

Color blindness is caused by…

Answer 22

damage of one or more cones in retina.

Question 23

Color blind damage is often due to X chromosome damage. (T or F)

Answer 23

True

Question 24

What are the types of color cones? (3)

Answer 24

1. Red
2. Green
3. Blue