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Eye Phys > The Eye and How It Works pt 2 > Flashcards

The Eye and How It Works pt 2 Flashcards

1
Q

OD

A

Right Eye.

Oculus dexter: OD

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2
Q

OS

A

Left Eye.

Oculus sinister: OS.

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3
Q

OU

A

Both Eyes.

Oculus uterque: OU.

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4
Q

PRN

A

When necessary/as needed.

Pro re nata: PRN.

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5
Q

STAT

A

Immediately.

Statim: STAT.

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6
Q

Gtts

A

Gtts.

Guttae: eyedrops.

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7
Q

SX

A

Sx.

Surgery. (can also mean symptoms)

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8
Q

Dx

A

Dx.

Diagnosis

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9
Q

Fusion

A

two eyes that work together to give one image. Delicate balance!

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10
Q

Binocular vision

A

Ability of the eyes to fuse two images into a single image.

Balance of motor and sensory function.

-Equal impulses to each eye.

-Contraction of muscle equivalent to relaxation of opposing.

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11
Q

Suppression

A

Ignoring of the blurred image. Clear image and blurred image cannot be fused.

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12
Q

Overlap

A

Seeing more with two eyes than one.

Apprrox 35° of vision is overlap

Locking device - Merges peripheral vision to ensure central fusion.

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13
Q

Fixation

A

Looking straight ahead.

Requires stability and good monocular function (each eye has to work independently).

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14
Q

Fixation can be impacted by (3)

A

Nystagmus.

Macular Disease.

Strabismus.

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15
Q

What is strabismus?

A

misalignment of 2 eyes not pointing in the same direction

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16
Q

diplopia

A

seeing double

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17
Q

What happens in strabismus? (4)

A

1- diplopia
2 - Amblyopia develops b/c stronger eye takes control
3 - one eye points in a different direction from other
4 - brain is forced to choose an eye to focus with

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18
Q

Fusion

A

both eyes focusing together

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19
Q

Fixation

A

One eye focusing

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20
Q

How is fusion disrupted?

A

by covering an eye

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21
Q

heterophoria

A

the direction the eyes point at rest

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22
Q

esophoria

A

eyes turned inward

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23
Q

exophoria

A

eyes turned outward

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24
Q

hyperphoria

A

one eye is pointed a little higher than the other

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25
Q

convergence

A

eyes come together to look at near objects (reading, etc)

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26
Q

Positions of Gaze.

A

Primary Positions - Straight-ahead position.

Secondary Positions - Horizontal or vertical movement (looking up, down, L or R)

Tertiary Positions - Oblique movement (eyeroll)

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27
Q

Duction

A

Movement of ONE eye from one position to another.

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28
Q

Version

A

Movement of two eyes in the same direction.

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29
Q

Lateral Rectus

A

Moves eye horizontally away from nose.

Abduction.

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30
Q

Medial Rectus

A

Moves eye towards nose.

Adduction.

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31
Q

Intorsion

A

Right Eye moves from 12:00 to 1:00.

Primary Action: right superior oblique.

Secondary Action: right inferior rectus.

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32
Q

Extorsion

A

Right Eye moves from 12:00 to 11:00.

Primary Action: right inferior oblique.

Secondary Action: right superior rectus.

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33
Q

Superior Rectus

A

Elevates eye.

Intorsion,
Adduction.

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34
Q

Inferior Rectus

A

Depresses eye.

Extorsion,
Adduction.

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35
Q

Superior Oblique

A

Intorts eye.

Depression,
Abduction.

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36
Q

Inferior Oblique

A

Extorts eye.

Elevation,
abduction.

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37
Q

Volition

A

Frontal lobe of brain.

rapid, high speed movement of the eye that ends quickly (like a quick eye turn)

Don’t get visual info from this

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38
Q

pursuit

A

watching something move (like watching a plane move across the sky)

occipital lobe

slow, smooth, gliding motion of eye - DO get visual information while moving

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39
Q

Vergence

A

Simultaneous ocular movements in which the eyes are directed to an object in the midline in front of the face.

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40
Q

Convergence.

A

Rotate inward.

Constriction of pupils.

Accommodation.

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41
Q

Divergence.

A

Rotate outward.

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42
Q

Accomomdative triad

A

convergence
pupillary constriction
accommodation

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43
Q

What happens in convergence in the accommodation triad?

A

alleviates diplopia (double vision) and moves the eye to an object

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44
Q

What happens in pupillary constriction in the accommodation triad?

A

formation of pinhole

45
Q

What happens in accommodation of accommodative triad?

A

brings object on retina

46
Q

monocular depth perception cues

A

Magnification (comparing size of 2 objects)

Confluence of parallel lines (railroad tracks)

Interposition of shadows (big vs small shadows)

Blue-gray mistiness of objects at greater distances.

Parallax (looking at movement of 1 object)

47
Q

stereopsis

A

Higher quality of binocular vision.

Each eye views at object at slightly different angle.

Therefore: Fusion of images occurs by combining slightly dissimilar images.

48
Q

Range of focus

A

Range an object can be seen without accommodation (20 feet or 6 meters).

aka - the distance where the eye doesn’t have to work to focus

49
Q

Range of Accommodation.

A

Distance an object can be carried to eye and kept in focus.

Continual readjustment.

50
Q

Power of accommodation.

A

Dioptric equivalent of that distance (range of accommodation)

51
Q

What stimulates accommodation

A

blurred image on retina

52
Q

measurement for accommodation

A

Range and power of accommodation.

Closest point of an accommodative target.

Range = cm.

Power = diopters.

52
Q

Steps of accommodation (4)

A

Object moves closer to the eye.

Light must be converged.

Contraction of ciliary muscles  zonular fibers relax.

Lens changes shape.

53
Q

6 pieces of the transparent pathway of light

A

1 -tears
2- cornea
3- aqueous humor
4 - iris
5- lens
6 - vitreous body

54
Q

three layers of tears

A

Oil/Lipid.

Aqueous.

mucin

55
Q

oil/lipid layer of tears

A

Outtermost layer.

Meibomian Gland.

Evaporation.

56
Q

Mucin.

A

Innermost layer.

Goblet cells.

Tiny irregularities.

Mirror-like finish.

56
Q

How much tears are produced daily?

A

.5-1 mL of tears produced daily.

56
Q

Aqueous.

A

Middle layer.

Lacrimal Gland.

Accessory lacrimal glands in conjunctiva.

Inorganic matter and salts water

57
Q

Where do tears go?

A

50% Evaporation.

Other 50%:
Inferior and superior puncta.

Nasal lacrimal duct.

Inferior meatus of nose.

58
Q

lysozyme

A

nonpathpgenic bacteria

59
Q

formation of tears

A

psychic (caused by emotion)
reflex (cause by uncomfortable retinal stimulation such as when your eyes are dialated)

60
Q

Cornea - as transparent pathway of light

A

light must go straight through all 5 layers

no opaque substance

61
Q

Where does cornea get nourishment since there are no blood vessels?

A

perilimbal vessels (where conjunctiva meets cornea)
tear film
aqueous humor

62
Q

edema

A

swelling

63
Q

cornea hydrated or not hydrated?

A

hydrated

64
Q

sclera - hydrated or not hydrated?

A

not hydrated

65
Q

What does the corneal epithelum do?

A

fast, regeneration of cornea

66
Q

what does corneal endothelium do?

A

creates a dam so that there is homeostasis in the eye

67
Q

What three layers of the cornea can regenerate?

A

epithelium (no scarring)
Bowman’s layer
Stroma

68
Q

Aqueous Humor location

A

between cornea and lens

69
Q

What is aqueous humor

A

clear, colorless, watery

70
Q

Where is aqueous humor formed?

A

ciliary process behind iris

71
Q

How does aqueous humor move?

A

constant circulation

72
Q

How is aqueous humor formed?

A

Posterior Chamber -> Pupil -> Anterior Chamber -> Trabecular Meshwork -> Schlemm’s Canal -> Aqueous Veins -> Veins -> Neck -> Heart.

Starts from blood, goes back to blood

73
Q

How is intraocular pressure measured?

A

tonometer

74
Q

What is normal intraocular pressure

A

13-20 mmHg

75
Q

Ocular hypertension

A

intraocular pressure too high

76
Q

what can change intraocular pressure

A

respiration (breathing can change pressure by 5 mm Mg)
pulsation
Daily change (2-3 mm Hg)

77
Q

When is intraocular pressure highest?

A

6am (generally thought to be due to dehydration)

78
Q

What does intraocular pressure depend on (2)

A

amount of aqueous humor
hydration

79
Q

What is the “shutter” of the eye

A

iris/pupil

80
Q

What does the pupil respond to (3)?

A

arousal (fear, anxiety, erotic stimulation)
direct
consensual (if one eye dilates, so does the other)

81
Q

What does excessive illumination do to the pupil

A

activates sphincter muscle to make pupil smaller

82
Q

What does poor illumination do do pupil?

A

Activates dilator muscles to make pupil larger and let more light in

83
Q

Two parts of lens

A

nucleus (inner part - formed by age 30)
cortex

84
Q

lens refraction

A

uniform index refraction - light gets bent 1 way going hrough lens

85
Q

What nourishes lens

A

aqueous surrounding it

86
Q

Vitreous body location

A

directly behind lens

87
Q

vitreous body is made of?

A

transparent gel - makes up about 2/3 of eye

88
Q

Function of vitreous body

A

shock absorber
“space between the film”

89
Q

scotopic

A

night vision
rods
125.000.000
dim light

90
Q

photopic

A

cones (red, green, blue)
straight ahead and color vision
fovea

91
Q

How do we adapt to dark?

A

rods - 30 minutes in dark for full activation

92
Q

rhodopsin

A

visual purple
destroyed by light
vitamin a

93
Q

light and the retina

A

Light.

Photoreceptors.

Bipolar cells.

Ganglion cells.

Retinal synaptic zone.

Axons.

Through optic nerve.

Chiasm.

Optic Tract.

Lateral Geniculate Body.

Occipital Lobe.

94
Q

positive after images

A

retinal images
short duration (microscopic movements)
little awareness due to constant eye movements
same color as last color seen

95
Q

negative afterimages

A

what you see when you have a flash of light from a picture
retinal photoreceptors are unresponsive after high intensity light
used to test for strabismus

96
Q

Three pigments of color

A

red, green, blue

97
Q

frequency of color blindness

A

males - 8%
females - less than .1%

98
Q

How does color blindness develop?

A

sex linked recessive trait

99
Q

trichromat

A

normal color vision

100
Q

anomalous trichromat

A

partial deficiency in 1 cone pigment

101
Q

protanomaly

A

deficiency in red
poor red-green and blue-green discrimination

102
Q

dueteranomaly

A

deficiency in green
poor green-purple and red-purple discrimination

103
Q

dicromat

A

complete deficiency in one pigment by preserves the remaining two pigments (protanopia, deuteranopia or tritanopia)

104
Q

protanopia

A

no red receptor

105
Q

deuteranopia

A

no green receptor

106
Q

tritanopia

A

no blue receptor

Eye Phys (3 decks)

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