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Acute Care in OT > Quiz: Low Vision & Visual Perception > Flashcards

Quiz: Low Vision & Visual Perception Flashcards

1
Q

Definition of Low Vision

A

A visual impairment, not correctable by standard glasses, contact lenses, medicine, or surgery, that interferes with a person’s ability to perform everyday activities

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2
Q

In the US, what is legal blindness defined as?

A
  • distance visual acuity of 20/200 or worse in the better seeing eye after best conventional correction\
  • also defined as a visual field less than or equal to 20º at the widest point
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3
Q

What is accommodation?

A

the process of lens thickening and thinning

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4
Q

Presbyopia

A

the flexibility of the lens fibers decreases and the lens becomes more rigid; accommodation becomes weaker; image falls in the back of the eyes; use a positive lens to fix it

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5
Q

What is the function of the vitreous chamber?

A

to support the retina

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6
Q

T or F: The surrounding retina is vital for central vision and defines a 180 degree half sphere of mainly rods.

A

False, vital for peripheral vision

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7
Q

Central Visual System

A
  • involves macula-fovea, central optic nerve and central occipital lobe
  • clear sight; color vision; reading and writing
  • 30 degree visual field (5-10 is macula-fovea)
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8
Q

Peripheral Visual System

A
  • involves peripheral retina, optic nerve and peripheral regions of the occipital lobe
  • provides us with info that tells us where we are in space
  • night vision; perception of motion, orientation and balance
  • used when we walk, run, drive and maintain balance
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9
Q

What does CN III (three) do?

A

“the rest are three”

  • eye elevation; eye depression; eye adduction; eye elevation and adduction
  • opens eyelid
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10
Q

What does CN VI (six) do?

A

“six goes out”

- eye abduction

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11
Q

What does CN IV (four) do?

A

“four down and in”

- eye depression and adduction

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12
Q

What does CN V (five) do?

A

“eye sensation”

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13
Q

What does CN VII (seven) do?

A

“close your eyelid”

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14
Q

Age Related Macular Degeneration

A
  • > 50 years old
  • affects macula
  • blurred vision, central scotomas, distorted vision, impairment of glare, color and contrast sensitivity
  • slow recovery of visual function after exposure to bright light
  • blind spot in that 30 degrees
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15
Q

Dry AMD

A
  • most common (75%)
  • can develop to wet
  • drusen or yellow spots on macular and geographic atrophy
  • slight less severe and slower processing
  • usually no treatment
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16
Q

Wet AMD

A
  • abnormal BV growth under macula
  • 25% of all AMD
  • more advanced, faster progression of vision loss
  • medication: injection into the vitreous
17
Q

Implantable Miniature Telescope (MIT)

A
  • treatment for AMD
  • take off lens and put magnifier inside to see better
  • Criteria:
    • greater than or equal to 75 yo
    • visual acuity: 20/160 to 20/800
    • have evidence of visually significant cateract
    • have adequate peripheral vision in the eye not scheduled for surgery
18
Q

Diabetic Retinopathy (DR)

A
  • after 10 - 15 years of diabetes; most will demonstrate
  • reduced delivery of oxygen to the retina cells and eye tissues
  • BV leak - hemorrhage
  • vasogenic factors cause new BVs to form
  • glasses prescription change frequently
  • may cause glaucoma
  • often leads to total blindness
19
Q

What are the treatments of Diabetic Retinopathy?

A
  • laser surgery; injection of corticosteroids, injection of anti-VEGF; vitrectomy
20
Q

Retinitis Pigmentosa

A
  • group of genetic eye conditions: progressive retina dystrophy
  • abnormality of photoreceptors or the retinal pigment epithelium
  • night blindness (defective dark adaptation)
  • reduction of visual field - tunnel vision
  • loss of central vision late in the course
  • pigment layer comes to the top of the retina –> then you can’t see
21
Q

Glaucoma

A
  • aqueous humour forms from ciliary body –> posterior chamber –> anterior chamber –> trabecular meshwork –> Schlemm’s canal
  • HTN inside the eye
  • damages optic nerve
  • reduced peripheral vision
  • can cause total blindness
  • open angle and close angle
  • cause is not known/ there is not one cause
22
Q

Open angle glaucoma

A
  • 90% of glaucoma; gradually progressive visual field loss and optic nerve changes
  • affects more asians and blacks
23
Q

Close angle glaucoma

A
  • 10%; sudden ocular pain; see halos around lights; red eye; very high intraocular pressure; sudden decreased vision and fixed, mid-dilated pupil
24
Q

Cataracts

A
  • opacity of the lens
  • blurred vision
  • sensitivity to glare
  • treatable: leave back layer –> remove the front and replace it with an artificial layer
25
Q

Visual Acuity

A
  • measure of the eye’s ability to distinguish object details and shape
  • Snellen test; biVABA
  • fovea is the region for maximum visual acuity –> primarily a function of cone receptors
26
Q

Visual Field

A
  • extent of space visible to the eye that is fixated straight ahead
  • measured in degrees from fixation
  • sensitive to color
27
Q

Color Sensitivity

A
  • the ability to perceive and distinguish between colors
  • results from stimulation of RGB cones
  • problem is in the macula (AMD: difficulties with similar colors)
28
Q

Dark Adaptation

A
  • process by which an eye adjusts to decreased illumination and becomes more sensitive to light
  • accomplished by photo-activation of rods and light adaptation is achieved by cones
29
Q

Contrast Sensitivity

A
  • ability to detect detail having subtle gradations in grayness between test target and background
  • increasing contrast helps reading and other daily activity
30
Q

Apraxia (optic)

A

inability to execute purposeful movement; cannot move eye to target

31
Q

Ataxia (optic)

A

inability to visually guide limbs (mislocalization when reaching or pointing for objects)

32
Q

Constructional apraxia

A

inability to copy or build a simple design (3 blocks –> cannot build)

33
Q

depth perception

A

inability to judge depths and distances

34
Q

figure ground

A

inability to distinguish foreground with background

35
Q

form perception/constancy

A

inability to judge variations in form, including visual form, visual closure, etc.

36
Q

visual scanning/visual attention (2 levels)

A
  1. an automatic/reflexive level (brain stem), like flash light
  2. a voluntary level (cortex) - gathering purposeful information
37
Q

spatial relations

A

inability to perceive the position of two or more objects in relation to self and to each other

38
Q

unilateral space neglect

A

inability to attend to or respond to meaningful sensory stimuli presented in the affected hemisphere

39
Q

Charles Bonnet Syndrome

A

visual hallucinations; about 1/3 of low vision patients develop this

Acute Care in OT (7 decks)

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