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Flashcards in Exam 2 Material Deck (189)
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1

Where is the visual center located in the brain?

Occipital lobe

Half of the neocortex is involved with processing visual information 

2

What protects the eye?

Protected by the bony orbital cavity and cushioned by fat 3/4 protected by bone, 1/4 protected by eyelids

3

Palpebral fissure

Where eyelids touch

4

Limbus

White goes into color; cornea and sclera

5

Pupil

Absence of tissue; aperture of the eye

6

Medial and lateral canthus

Corners of the eye

7

Conjunctiva (palpebral and bulbar)

Always clear unless pathology is present

8

Lacrimal apparatus

Tear glands

Palpated in exam to determine if there is lacrimal reguritation

 

9

Extraocular muscles

Multiple muscles that are attached to the eyeball that twists and turn the eyeball to where it needs to go.

Innervated by cranial nerves III, IV, and VI

CN IV allows eyes to look toward the nose

CN VI lets the eyes look laterally 

CN III does all other movements 

10

If eye is not moving correctly, what is the likely cause?

Innervation problem. Muscles normally are fine unless there is trauma.

11

What cranial nerve innervates the extraocular muscles that moves the eyes laterally?

CN VI

12

What cranial nerve innervates the extraocular muscles that moves the eyes toward the nose

CN IV

13

Layers of the eye

The eye is a sphere of three concentric coats 

1. Outer layer -sclera

2. Middle layer - choroid: ciliary body, iris, pupil, lens, anterior chamber

3. Inner layer - retina: optic disc, retinal vessels, macula

14

What is the center of vision in the eye

Macula 

Does not coincide with where the optic nerve innervates

Dense cones and rods 

Fovea: center of the macula - highest density of cones, no rods

 

15

What is in the retina

Macula (center of vision) and optic disc (where the optic nerve is attached to the eye)

16

Visual reflexes

  • Pupillary light reflex (direct light reflex vs consensual light reflex)
    • Light causes pupils to constrict 
    • Both eyes should constrict evenly with light shown only in one eye 
  • Accomodation 

17

Vision pathway 

 

Light  to cornea to lens to retina to nerve impulses to optic nerve to visual cortex

18

What happens to depth perception when blind in one eye?

Do not have depth preception 

19

Health history questions for eyes

  • Vision difficulty? acuity, blurring, blind spots
  • Pain 
  • Strabismus, diplopia
  • Redness, swelling
  • Watering, discharge
  • Past history of eye problem 
  • Glaucoma 
  • Use of glasses or contact lenses 
  • Self-care behaviors - make up?

20

Equipment needed for Eye Exam

  • Snellen or Rosenbaum 
  • Opaque card 
  • Penlight 
  • Ophthalmoscope

21

Snellen/Rosenbaum

Tests visual acuity (CN II)

 

22

Myopia

  • Near sighted
  • Flatter eyeball; more oblong
  • Light focuses in front of the retina
  • Develops in childhood 

23

Hypermyopia

  • Far-sighted
  • Retina is too high
  • Light focuses behind the retina
  • Develops in childhood

24

How do glasses help with vision acuity?

Change the way the light foces so that it is cetnered on the macule

Hyperopia uses convex lenses

Myopia uses concave lenses

25

What is an astigmatism?

  • Cornea or lens are curved irregularly/enevenly (not round)
  • Causes a fuzzy or distorted vision
    • Refraction of light does not focus the right way 
  • Often causes halos and glare at night 
  • Sometimes can be corrected 
  • Brain learn to compensate 

26

Corneal Light Reflex (Hirschberg Test)

  • Shine a light in the middle of the nose and see where the light reflects
  • If pupils are not in the same position, the light will reflect in different places 
  • Not about being symmetric, it is about being in the same spot
  • May look cross eyed, but not 

27

Cover Test

  • Detects small degrees of stabismus (lazy eye) by interrupting fusion reflex that normally keeps eyes parallel 
  • Ask the person to stare straight ahead to your nose even though gaze may be interrupted 
  • With a card, cover one eye
    • Not uncovered eye normal response: steady fixed gaze
    • If muscle weakness exists, covered eye will drift into a relaxed position 
    • Uncover the eye and observe it for movement - it should be straight ahead; if it jumps to reestablish fixation, eye muscle weaness exists 

28

Causes of strabismus

Lazy eye

Eyeball is not turned in the right direction (typically a nerve issue, can be muscular)

Eye patches are used to cover the good eye to try to strengthen the bad one 

29

6 Cardinal Fields of Gaze

Tests muscles and their innervations 

Can tel if someone has a beat - neurological impairment

30

PERRLA

  • Pupils
  • Equal 
  • Round
  • Ractive
  • Light 
  • Accomodation: pupils dilate at a distant and constrict and converge when object is closer