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Lewis Chapter 20: Assessment of Visual and Auditory Systems

Terms in this set (26)

What are the external structures of the eye?
-eyebrows
-eye lids
-eye lashes
-conjunctiva
-cornea
-sclera
-lacrimal system
-extraocular muscles
What are the internal structures of the eye?
-iris
-lens
-ciliary body
-choroid
-retina
Name the 3 layers of the eyeball
-outer: sclera and cornea
-middle: iris, choroid, ciliary body
-inner: retina
aqueous humor
-clear watery fluid found in the anterior chamber of the eye
***nourishes the cornea and lens
What is the normal range of IOP?
10-21 mm Hg
Which condition is caused by increased IOP?
glaucoma
How is the lens shape modified?
by the ciliary body
*part of accommodation
vitreous humor
transparent gel-like fluid found in the posterior cavity
refractive error
when light does not focus properly
myopia
nearsightedness
*near objects clearly, blurred vision in the distance
hyperopia
farsightedness
*far objects clearly, blurred vision close up
astigmatism
uneven curvature of the cornea
presbyopia
loss of accommodation, unable to focus on near objects
*appears around age 40
What 3 structures are physical barriers to dust and foreign particles?
-eyebrows
-eye lids
-eye lashes
Which cranial nerve opens the eyelid?
CN III (oculomotor)
Which cranial nerve closes the eyelid?
CN VII (facial)
conjunctiva
"pocket" under the eyelid
sclera
"whites" of the eyes
*collagen fibers; protect internal structures
What are the 6 layers of the cornea?
-epithelium
-bowman's layer
-stroma
-descemet's membrane
-dua's layer
-endothelium
tear film
moistens the eye and provides oxygen to the cornea
iris
colored part of the eye
pupil
allows light into the eye
*constriction-CN III
*dilation-CN V
retina
rods and cones
rods
dim or darkened environment
Which area of the retina provides the sharpest visual acuity? Why?
fovea centralis; center of the macula, made of densely packed cones
What type of drug is used often to treat glaucoma?
beta-blockers
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