HLTH 2501: the eye Flashcards

1
Q

what is the eye protected by?

A

the body orbit of the skull

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2
Q

muscle of the upper eyelid

A

the levator palpebrae superioris

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3
Q

what is the levator palpebrae superior controlled by?

A

the oculomotor nerve (III)

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4
Q

cranial nerves controlling the extrinsic eye muscles

A

III, IV, and VI

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5
Q

outer layer of the eye

A

is a tough, fibrous layer consisting of the cornea and the sclera

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6
Q

middle layer of the eye

A

aka the uvea; is made up of the choroid, the ciliary body, and iris

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7
Q

the choroid

A

is a dark, vascular layer that absorbs the light, preventing reflection

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8
Q

what supplies blood to the retina?

A

the choroid

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9
Q

ciliary processes

A

secrete aqueous humor

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10
Q

two muscles in the iris

A

the circular (contracts) and the radial (dilates)

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11
Q

lens

A

is a biconvex structure made up an elastic capsule surrounding an orderly alignment of fibres

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12
Q

retina

A

the inner layer that consists of the pigmented layer and the neural layer

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13
Q

fovea centralis

A

is a depression within the macula lutea that contains many cones and provides the most acute vision

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14
Q

colour blindness

A

is common in males and results from a deficit of one type of cone owing to an abnormal gene on the X chromosome

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15
Q

posterior cavity

A

is the space between the lens and the retina and contains the vitreous humor

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16
Q

anterior cavity

A

is between the cornea and the lens and is filled with aqueous humor and is further divided into the anterior chamber (cornea to iris) and the posterior chamber (iris to lens); the chambers are connected through the pupil

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17
Q

where is aqueous humor secreted from and where is it drained into?

A

secreted from the ciliary processes into the posterior chamber and drained from the anterior chamber by the canal of Schlemm

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18
Q

what does the aqueous humor supply?

A

nutrients to the lens and cornea because they lack blood vessels

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19
Q

complications of conjunctivitis

A

meningitis, cellulitis, septicemia, otitis media, pneumonia, and keratitis

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20
Q

otitis media

A

ear infection

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21
Q

what provides depth perception?

A

the double image projected rom different angles by both eyes

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22
Q

what pass through the optic disc?

A

the central retinal artery and vein

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23
Q

diagnostic tests for eye function

A

the snellen chart, visual field tests, tonometry, ophthalmoscope, gonioscopy measures, and muscle function and coordination

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24
Q

the snellen chart

A

consists of line of progressively smaller letters and numbers, measuring visual acuity

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25
Q

what are visual field tests used for?

A

to check central and peripheral vision

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26
Q

tonometry assessment

A

assess intraocular pressure by checking the resistance of the cornea

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27
Q

ophthalmoscope

A

is used to examine the interior structures of the eyes

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28
Q

gonioscopy

A

measures the angle of the anterior chamber

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29
Q

myopia

A

is nearsightedness and occurs when the image is focused in front of the lens; corrected with concave lens

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30
Q

hyperopia

A

is farsightedness and occurs when the image focuses behind the retina; is corrected with convex lens

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31
Q

presbyopia

A

is farsightedness associated with aging when the loss of elasticity reduces accommodation

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32
Q

astignmatism

A

develops from an irregular curvature in the cornea or lens

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33
Q

strabismus

A

results from a deviation of one eye, resulting in double vision; this is cross-eye

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34
Q

diplopia

A

aka double vision

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35
Q

what may strabismus be caused by?

A

a weak or hypertonic muscle, a short muscle, or a neurological defect

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36
Q

amblyopia

A

is the suppression by the brain of the visual image from the affected eye

37
Q

nystagmus

A

is an involuntary abnormal movement of one or both eyes; can be back and forth, jerky, or circular

38
Q

what does nystagmus result from?

A

neurologic causes, inner ear or cerebellum disturbances, or from drug toxicity

39
Q

ptosis

A

is paralysis of the upper eyelid

40
Q

stye

A

is an infection involving a hair follicle on the eyelid, forming a swollen, red mass which may be uncomfortable when blinking

41
Q

what is a stye caused by

A

usually a staphylococci

42
Q

conjunctivitis causative organisms

A

most are bacteria or an adenovirus, but can also be herpes simplex virus, varceilla-zoster virus, and coronavirus

43
Q

conjunctivitis

A

is a superficial inflammation or infection lining the eyelids and covering the sclera

44
Q

what causes pink eye?

A

S aureus

45
Q

pinkeye

A

is spread by fingers or towels and causes the sclera of the eye and eyelid to appear red and for purulent discharge to develop

46
Q

contact lenses and infection

A

can cause conjunctivitis and keratitis

47
Q

what infections may cause infection of the eyes in newborns?

A

chlamydia trachomatis and gonorrhea; this causes redness and heavy discharge from the eyes

48
Q

trachoma

A

is a infection of the eyes that causes follicles to develop on the inner surface if the eyes and is highly contagious

49
Q

what is trachoma caused by?

A

chlamydia trachomatis

50
Q

what happens if trachoma is not fully treated?

A

the eyelids become scarred and the lashes turn inward to abrade the cornea

51
Q

most common cause of vision loss

A

trachoma

52
Q

symptoms of trachoma

A

scratchy eye, no exudate, and pearl-like follicles in upper eyelid

53
Q

keratitis

A

is an inflammation of the cornea, usually accompanied by severe pain and photophobia (this occurs because the cornea has numerous pain receptors)

54
Q

what nerve supplies the pain receptors of the cornea?

A

trigeminal nerve V

55
Q

causes of keratitis

A

can be infection or injury, often caused by herpes simplex virus

56
Q

complications of keratitis

A

there is an increased risk of ulceration eroding the cornea and scar tissue interfering with vision, and possibly causing vision loss

57
Q

what may damage to the cornea result from?

A

abrasions from foreign bodies, a damaged contact lens, or objects directly scratching the cornea

58
Q

glaucoma

A

results from increased intraocular pressure caused by an excessive accumulation of aqueous humor and is common with aging

59
Q

narrow-angle glaucoma

A

occurs when the angle between the cornea and the iris in the anterior chamber is decreased by factors such as an abnormal anterior insertion of the iris

60
Q

acute glaucoma

A

may occur when there is a sudden increase in intraocular pressure and is common with pupil dilation; this is narrow-angle

61
Q

chronic glaucoma

A

is also wide-angle glaucoma and occurs when the trabecular network and canal of schlemm become obstructed and the outflow of aqueous humor gradually diminishes; the blood flow to the retinal cells also decreases

62
Q

causes of chronic glaucoma

A

can be a developmental abnormality, aging, or scar tissue from trauma or infected

63
Q

signs of chronic glaucoma

A

increased intraocular pressure, loss of peripheral vision, corneal edema which leads to blurred vision, and halos around light

64
Q

what may trigger acute glaucoma

A

adrenergic drugs such as those used for colds or hay fever (vasoconstrictors or congestion), stress, and prolonged periods in dark rooms

65
Q

signs of acute glaucoma

A

eye eye, nausea, headache, blurred vision, and bulging cornea

66
Q

chronic glaucoma treatment

A

regular administration of eyedrops, constricting the pupil, drugs to reduce intraocular pressure (those that inhibit carbonic anhydrase), or laser trabeculoplasty

67
Q

example of eyedrops

A

timolol or betaxolol

68
Q

treatment for acute glaucoma

A

surgery to remove part of the iris or to open a passageway for drainage into the canal of schlemm or laser iridotomy

69
Q

function of laser trabeculoplasty

A

deepens the anterior chamber and thus increases the drainage of aqueous humor

70
Q

cataract

A

occurs when the normally clear lens becomes cloudy and thus interferes with light transmission

71
Q

causes of cataracts

A

degeneration related to aging, excessive exposure to sunlight, blows to the eyes, or material infections related to rubella or toxoplasmosis

72
Q

what material infections may cause cataracts?

A

rubella or toxoplasmosis

73
Q

indicator of cataracts

A

blurred vision that progresses over the visual field and becomes darker

74
Q

treatment for cataracts

A

damaged lens can be removed and replaced by an artificial one

75
Q

detached retina

A

is an acute problem that occurs when the retina tears away from the underlying choroid because of marked myopia, degeneration with aging, or scar tissue

76
Q

what is the result of a detached retina?

A

the tear allows vitreous humor to flow behind the loose retinal portion, causing a cease of function of the retina as its blood supply is derived from the choroid

77
Q

signs of a detached retina

A

no pain, but may begin with light or dark floating sports, and that a darkened or blind area that increases in size over time

78
Q

treatment for a detached retina

A

surgery such as scleral buckling or laser therapy closes holes and reattaches the retina

79
Q

macular degeneration

A

is a common cause of visual loss in the elderly due to degeneration at the fovea centralis, causing a lack of nutrients to pass from the choroid

80
Q

causes of macular degeneration

A

genetic factors and environmental exposure (ex. UV rays and drugs)

81
Q

2 types of macular degeneration

A

dry (atrophic AMD) or wed (exudative AMD)

82
Q

dry macular degeneration

A

is more common and occurs when deposits forms in the retinal cells, gradullary destroying them

83
Q

wet macular degeneration

A

occurs from neovascularization occurs, with the formation of abnormal, leaky blood vessels that gradually destroy the retina

84
Q

diagnosis for macular degeneration

A

visual field tests and angiography

85
Q

signs of macular degeneration

A

central vision with high acuity becomes blurred, then is lost and depth perception is affected; peripheral vision remains the same

86
Q

treatment for dry macular degeneration

A

optimal nutrition and a high dose of antioxidants and zinc

87
Q

treatment for wet macular degeneration

A

photodynamic therapy, the drug pegaptanib, and therapy using anti vascular endothelial growth factor

88
Q

photodynamic therapy

A

is photosensitive drug plus laser that seals off neovasculature to treat wet AMD