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MedTerm Mod17 *Eye*
Terms, Abbreviations, & Meanings
Question | Answer |
---|---|
AMD | age-related macular degeneration |
HEENT | head, eyes, ears, nose, & throat |
IOL | intraocular lens |
IOP | intraocular pressure |
LASIK | laser in situ keratomileusis |
OD | right eyeLatin: oculus dexterDoctor of Optometry (optometrist) |
OS | left eyeLatin: oculus sinister |
OU | both eyesLatin: oculus uterque |
PERRLA | pupils equal, round, reactive to light & accommodation |
POAG | primary open-angle glaucoma |
PRK | photorefractive keratectomy |
VA | visual acuity |
VF | visual field |
accomodation | normal adjustment of eye to focus on objects from far to near |
anisocoria | inequality in size of pupils |
anterior chamber | space behind cornea & in front of lens & iris; contains aqueous humor |
aphakia | absence of lens of eye |
aqueous humor | fluid produced by ciliary body, helps to maintain shape of eyeball |
chroid | middle layer of eye, thin membrane with rich supply of blood vessels |
ciliary body | structure on each side of lens that connects choroid & iris |
contains muscles that control shape of lens | the ciliary body |
cone | photoreceptor cell in retina |
responsible for color & central vision | cone |
conjuctiva | delicate mucous membrane lining inner surface of eyelids & anterior part of eye |
cornea | fibrous transparent layer of clear tissue that extends over anterior portion of eyeball |
corneascleral | pertaining to cornea & sclera, white of the eye |
fovea centralis | small depression in middle of macula; area of clearest vision |
hypertensive retinopathy | disease of retina due to high blood pressure |
intraocular | pertaining to within the eye |
iridic | pertaining to the iris |
iris | contractile disc that forms colored, pigmented portion of eye, by the ciliary body, surrounding the pupil |
lacrimal | pertaining to tears |
lacrimation | production of tears |
lens | highly elastic, transparent biconvex body behind pupil of eye; surround & supported by fibers arising from ciliary body |
macula | yellowish region on retina lateral to & slightly below optic disc |
contains fovea centralis | macula |
miosis | contraction of pupil of the eye |
mydriasis | widening of pupil of the eye |
ophthalmic | pertaining to the eye |
optic chiasm | point at which optic nerve fibers cross in brain |
optic disc | region at back of eye where optic nerve meets retina |
optic nerve | rod & cone cells of retina to cerebral cortex in occipital lobe of the brain |
palpebral | pertaining to an eyelid |
pupil | circular opening in middle of iris; dark, central portion of the eye |
pupillary | pertaining to the pupil of the eye |
refraction | bending of light rays as they pass through cornea, lens, & fluids of eye |
retina | thin, delicate membrane continuous with optic nerve; sensitive nerve cell layer of eye |
rod | photoreceptor retinal cell; essential for seeing objects in low light & peripheral vision |
sclera | tough outer membrane that helps to maintain shape of eyeball & attached to the muscles that moce the eye |
scotoma | blind spot in the field of vision |
thalamus | relay center in brain through which optic nerve fibers pass on way to cerebral cortex |
uvea | vascular layer of the eye, including iris, choroids & ciliary body |
viterous humor | soft, jelly-like material that fills the posterior cavity & preserves eyeball shape |
the eye is one of a pair of special sense organs that | converts the energy of light into electrical nerve impulses and transmits those signals to the brain |
The structures of the eye don't merely receive a light stimulus they | adjust the incoming light and adapt to it to form the clearest image |
The eyes are contained in | two bony orbits at the front of the skull |
external structure of the eye are | the eyelids, eyebrows & eyelashes |
lacrimal glands | produce tears that moisten eye & eye muscles |
there are three | fibrous layers covering eyeball |
white of the eye | sclera |
convex, transparent structure through which light passes to other parts of the eye | the cornea |
anteriorly the chorois is joined to | the iris |
muscles of the iris constrict & dilate the pupil in response | to the intensity of light |
Contraction or relaxation of the ciliary body changes | the shape and size of the lens |
fundus | inner posterior sirface of eye including retina & its structures and optic disc & macula lutea |
macula lutea is another term for | the macula |
multilayered structure, outermost layer of which contains light-sensitive cells-rods and cones | the retina |
optic disc is also called | the blind spot |
only area of retina that is not sensitive to light | the optic disc |
anterior cavity consist of | anterior & posterior chambers |
anterior cavity contains | the aqueous humor |
nourishes the iris, lens & cornea | aqueous humor |
posterior cavity occupies | all internal space behind the lens |
process that brings light rays into focus on retina & stimulates the rods & cones | refraction |
angle of refraction varies with | density of structure through which light rays pass |
refracting media of the eye are | the cornea, aqueous humor, lens & vitreous humor |
in accommodation the lens flattens | to perceive objects that are distant |
in accommodation the lens flattens because | the ciliary body relaxes |
in accommodation the lens thickens, or becomes rounded | to perceive objects that are near |
in accommodation the lens thickens, or becomes rounded, because | the ciliary body contracts |
when muscles of iris contract, the pupil constricts, which | eliiminates light rays that cannot be sufficiently refracted to focus on retina |
contraction of the iris, causing pupil constriction, is | a function to natrually protect the retina |
in addition to refraction. accommodation & constriction, accurate vision relies on | the coordinated/parallel movement of the eyes by the eye muscles |
rods & cones of retina contain chemicals that undergo changes in | the presence of light |
chemical changes, of rods/cones, produce | nerve impulses |
nerve impulses produced by rods/cones are transmitted to the brain and | interpreted as visual images |
cylindrical cells that enable detection of low-intensity light | rods |
most of 120 million rods of eye are located | around periphery of retina |
there are about 6.5 million cones which produce vision in bright light and | help us to see color |
how many types of cones in retina? | three |
each cone in retina is | sensitive to one of three primary colors |
Color blindness occurs when there is | an absence of cones in the retina |
a defect in production of the chemicals cones contain causes | color blindness |
The most common form of color blindness affects the ability to | distinguish reds from greens |
impulses are conveyed along the | optic nerve |
the optic nerve sends impulses along | the optic chiasm |
at the junction of the optic nerve and optic chiasm fibers from each optic nerve | cross over to the other side |
fibers from the each visual field of eye form the | left/right optic tract |
impulses move acros each optic tract to | the visual cortex in the occipital lobe |
occipital lobe is an area in posterir of brain where | visual stimuli is interpreted |
when the images from both eyes fuse in brain the produce | a single 3D image |
binocular vision | use of both eyes together, without diplopia |
covergence is | the movement of the eyes in unison toward a common point of fixation |
the ability to see one image using both eyes is because | convergence allows us to have binocular vision |