Chapter 17 The Language of Medicine

accomodation

normal adjustment of the eye to focus on objects from far to near. The ciliary body adjust the lens (rounding it) and the pupil constricts. When the eye focuses from near to far, the ciliary body flattens the lines and the pupil dilates.

anterior chamber

area behind the cornea and in front of the lens and iris. Contains the aqueous humor.

aqueous humor

fluid produced by the ciliary body and found in the anterior chamber. A humor is any body fluid, including blood and lymph.

biconvex

Consisting of 2 surfaces that are rounded, elevated, and curved evenly, like part of a sphere. The lens of the eye is a biconvex body.

choroid

Middle, vascular layer of the eye, between the retina and the sclera.

ciliary body

Structure on each side of the lens that connects the choroid and iris. It contains ciliary muscles, which control the shape of the lens, and it secretes aqueous humor.

cone

Photoreceptor cell in the retina that transforms light energy into a nerve impulse. Responsible for color and central vision.

conjunctiva

Delicate membrane lining the eyelids and covering the eyeball.

cornea

Fibrous transparent layer of clear tissue that extends over the anterior portion of the eyeball.

fovea centralis

Tiny pit or depression in the retina that is the region of clearest vision.

fundus of the eye

Posterior, inner part of the eye; visualized with an ophthalmoscope.

iris

Pigmented (colored) layer that opens and closes to allow more or less light into the eye. The central opening is the pupil.

lens

Transparent, biconvex body behind the pupil of the eye. It bends (refracts) light rays to bring them into focus on the retina.

macula

Yellowish region on the retina lateral to and slightly below the optic disc; contains the fovea centralis, which is the areas of clearest vision.

optic chiasm

Point at which optic nerve fibers cross in the brain.

optic disc

Region at the back of the eye where the optic nerve meets the retina. it is the blind spot of the eye because it contains only nerve fibers, no rods or cones, and is thus insensitive to light.

optic nerve

Cranial nerve carrying impulses from the retina to the brain (cerebral cortex).

pupil

Central opening of the eye, surrounded by the iris, through which light rays pass. It appears dark.

refraction

Bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina.

retina

Light-sensitive nerve cell layer of the eye containing photoreceptor cells (rods and cones).

rod

Photoreceptor cell of the retina essential for vision in low light and for peripheral vision.

sclera

Tough, white outer coat of the eyeball.

thalamus

Relay center of the brain. Optic nerve fibers pass through the thalamus on their way to the cerebral cortex.

vitreous humor

Soft, jelly-like material behind the lens in the vitreous chamber; helps maintain the shape of the eyeball.

aque/o

water

blephar/o

eyelid

conjunctiv/o

conjunctiva

cor/o

pupil

corne/o

cornea

cycl/o

ciliar body or muscle of the eye

dacry/o

tears, tear duct

ir/o, irid/o

iris (colored portion of the eye around the pupil)

kerat/o

cornea

lacrim/o

tears

ocul/o

eye

ophthalm/o

eye

opt/o, optic/o

eye, vision

palpebr/o

eyelid

papill/o

optic disk; nipple-like

phac/o, phak/o

lens of the eye

pupill/o

pupil

retin/o

retina

scler/o

sclera (white of the eye); hard

uve/o

uvea; vascular layer of the eye (iris, ciliary body, and choroid)

vitre/o

glassy

ambly/o

dull, dim

dipl/o

double

glauc/o

gray

mi/o

smaller, less

mydr/o

widen, enlarge

nyct/o

night

phot/o

light

presby/o

old age

scot/o

darkness

xer/o

dry

-opia

vision

-opsia

vision

-tropia

to turn

astigmatism

defective curvature of the cornea or lens of the eye

hyperopia (hypermetropia)

farsightedness

myopia

nearsightedness

presbyopia

impairment of vision as a result of old age

cataract

clouding of the lens, causing decreased vision

chalazion

small, hard, cystic mass (granuloma) on the eyelid

diabetic retinopathy

retinal effects of diabetes mellitus include microaneurysms, hemorrhages, dilation of retinal veins, and neovascularization (new blood vessels form in the retina)

glaucoma

Increased intraocular pressure results in damage to the retina and optic nerve with loss of vision

blepharitis

Inflammation of eyelid, causing redness, crusting, and swelling along lid margins.

dacryocystitis

blockage, inflammation, and infection of a nasolacrimal duct and lacrimal sac, causing redness and swelling in the region between the nose and the lower lid.

ectropion

outward sagging and eversion of the eyelid, leading to improper lacrimation and corneal drying and ulceration.

entropion

inversion of the eyelid, causing the lashes to rub against the eye; corneal abrasion may result

hordeolum (stye)

small, superficial white nodule along lid margin due to infection of a sebaceous gland

ptosis

drooping of upper lid margin from neuromuscular problems or trauma

xanthelesma

raised yellowish plaque on eyelid caused by lipid disorder

hordeolum (stye or sty)

localized, purulent, inflammatory staphylococcal infection of a sebaceous oil-producing gland in the eyelid

macular degeneration

progressive damage to the macula of the retina

nystagmus

repetitive rhythmic movements of one or both eyes

retinal detachment

2 layers of the retina separate from each other

strabismus

abnormal deviation of the eye

fluorescein angiography

intravenous injection of fluorescein (a dye) followed by serial photographs of the retina through dilated pupils

ophthalmoscopy

visual examination of the interior of the eye

slit lamp microscopy

examination of anterior ocular structures under microscopic magnification

visual acuity test

clarity of vision is assessed (Snellen chart)

visual field test

measurement of the entire scope of vision (peripheral and central)

keratoplasty

surgical repair of the cornea

laser photcoagulation

intense, precisely focused light beam (argon laser) creates an inflammatory reaction that seals retinal tears and leaky retinal blood vessels

LASIK

use of an excimer laser to correct errors of refraction (myopia, hyperopia, and astigmatism)

phacoemulsification

ultrasonic vibrations break up the lens; the pieces are then aspirated through the ultrasonic probe

scleral buckle

suture of a silicone band to the sclera over a detached portion of the retina

external auditory canal

channel that leads from the pinna to the eardrum

auditory meatus

auditory canal

auditory nerve fibers

carry impulses from the inner ear to the brain (cerebral cortex). These fibers compose the vestibulocochlear nerve (cranial nerve VIII)

auditory tube

channel between the middle ear and the nasopharynx; eustachian tube

auricle

flap of the ear; the protruding part of the external ear, or pinna

cerumen

waxy substance secreted by the external ear; earwax

cochlea

snail shell-shaped, spirally wound tube in the inner ear; contains hearing sensitive receptor cells

endolymph

fluid within the labyrinth of the inner ear

eustachian tube

auditory tube

incus

second ossicle (small bone) of the middle ear; means anvil

labyrinth

maze-like series of canals of the inner ear. Includes the cochlea, vestibule, and semicircular canals

malleus

first ossicle of the middle ear; means hammer