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orbit
bony cavity that houses the eyeball, eye muscles, nerves and blood vessels
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wall of eyeball has 3 layers
- 1: sclera
- 2: cornea
- 3: choroid layer
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sclera
white outer layer of the eyeball
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cornea
anterior portion of the eye, where the sclera forms a transparent dome structure
avascular, but has nerve endings with pain fibers
protects the front part of the eye from injury and is the first structure of the eye that refracts light rays
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Choroid layer
lies behind the sclera and has blood vessels
Ciliary body: (muscle) anterior portion of the choroid
- iris: also anterior portion of eye.
- colored portion of the eye
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retina
lines the poster 2/3 of the eyeball
contains rods (light) and cones (colors)
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fovea
(part of retina) depression near the center of the retina.
area with sharpest vision (lots of cones)
Macula: yellowish surrounding of the fovea. lots of cones here too
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rupture of cornea
keratorrhexis
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laser keratotomy
Used to correct vision
shallow, bloodless, hairline, radial incisions are made using a laser in the outer portion of the cornea...this allows the cornea to flatten and helps to correct nearsightedness
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pupil
opening in the center of the iris
controls amount of light entering the eye by contractions and dilations
constriction of the pupil permits a sharper near vision
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photopigments
light sensitive molecules that convert light energy into electrical impulses.
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optic disk
where retinal nerve fibers unity and cut across through the wall of the eyeball as the optic nerve
optic disk has to rods or cones (blind spot)
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paralysis of eye muscles
ophthalmoplegia
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conjunctiva
thin mucous-secreting membrane that lines the interior surface of the eyelids and the exposed anterior surface of the eyeballs
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blepharoplasty
surgical procedure to remove wrinkles from the eyelids
excessive skin around he upper eyelids may cause a decrease or lack of peripheral vision
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erythropia
condition in which objects that are not red appear to be red
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xanthopia
condition in which objects that are not yellow appear to be yellow
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diplopia
double vision
both eyes are not in focus
can occur with brain tumors, strokes, head trauma, and migraine headaches
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myopia
nearsightedness
if the eyeball is too long, the visual images falls in front of the retina, causing difficult seeing objects that are far away
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hyperopia
farsightedness
occurs when the lens focuses the visual image beyond the retina causing difficulty in seeing objects that are close
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blepharoptosis
common after a stroke, because the muscles leading to the eyelids become paralyzed
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lacrimal gland
located above the outer corner of each eye
these glands produce tears, which keep the eyeballs moist
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lacrimal sac
collects and drains tears into nasolacrimal duct
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dacryanenalgia
pain in the tear gland
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dacryadenitis
inflammation of a tear gland
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