CHAPTER 16 OKAY OKASHDAHD

Ophthalmologist

Medical specialist (MD) in the diagnosis and treatment of diseases of the eye.

Optometrists (ODs)

Who are doctors of optometry and are skilled in the measurement of vision. They are not medical doctors and cannot prescribe medicaion

Opticians

License to make corrective lenses, adjust and repair spectacles, and fit contact lenses.

Otologist

Medical specialist in diseases of the ear

Otorhinolaryngologist

Medical specialist (MDs) in diseases of the ear, nose, and throat (ENT)

Audiologist

Who evaluate hearing function

Eyebrows

Keeps sweat from running into the eye and function in nonverbal communication

Eyelids

Consist mostly of muscle that fans out from eye eyelid onto the forehead and cheek to open and close the eyelids. They are covered in the body’s thinnest layer of skin.

Tarsus

A flat, fibrous connective tissue layer in he eyelid, who ducts open along the edge of the eyelid.

tarsal glands

Are found within the tarsus, with ducts open along the edge of the eyelid. They secrete an oily fluid that keeps the eyelids from sticking together.

Eyelashes

Strong hairs that help keep debris out of the eyes. They arise on the edge of the lids from the hair follicles.

Canthi

Are the two corners where the upper and lower eyelid meets

Conjunctiva

A transparent mucous membrane that lines the lines the inside of both eyelids and covers the front of the eye except the central portion, the cornea.

Lacrimal (tear) gland

Located in the upper, lateral corner of the orbit, secretes tears

Short lacrimal ducts

Carry the tears at the medial corner of the eye

Nasolacrimal duct

Carries the tears into the nose, from where they are swallowed.

Canthus

Corner of the eye where upper and lower lids meets

Canthi

Canthus plural

Conjunctiva

Inner lining of the eyelids

Conjunctival

Pertaining to the conjunctiva

Extrinisc

Muscles that are located on the outside of the eye.

Intrinsic

Muscles that are located inside the eye

lacrimal

Pertaining to tears

Lacrimal duct

Carries tears to the conjunctiva

Lacrimal sac

Where tears leave the eye at the medial corner

Nasolacrimal duct

Passage from the lacrimal sac to the nose

Lysozyme

Enzyme that dissolves the cell walls of bacteria

Orbit

The bony socket that holds the eyeball

Orbital

Pertaining to the orbit

Periorbital

Pertaining to tissues around the orbit

Stereopsis

Three-dimensional vision

Tarsus

The flat fibrous plate that gives shape to the outer edges of the eyelids

Tarsal

Pertaining to the tarsus

Ciliary body

Muscles that make the lens of the eye thicker and thinner

cornea

the central, transparent part of the outer coat of the eye covering the iris and pupil

iris

colored portion of the eye with the pupil in its center

lens

transparent refractive structure behind the iris

pupil

the opening in the center of the iris that allows light to reach the lens

pupillae

pupil plural

pupillary

pertaining to the pupil

refract

make a change in direction of, or bend, a ray of light

refraction

the change in direction of a ray of light when it passes from one optic medium to another

retina

light-sensitive innermost layer of eyeball

retinal

pertaining to the retina

sclera

fibrous outer covering of the eyeball and the white of the eye

scleral

pertaining to the sclera

sphincter

band of muscles that encircles an opening; when it contracts, the opening squeezes closed

optic nerve

a bundle of more than a million nerve fibers, transmits these impulses to the visual cortex at the back of the brain.

optic disc

The area where the optic nerve leaves the retina. has no rods and cones, the optic disc cannot form images and is called the blind spot.

macula lutea

lateral to the optic disc at the back of the retina is a circular, yellowish region

fovea centralis

In the center of the macula is a small pit. has 4,000 tiny cones and no rods. Each cone has its own nerve fiber, and this makes the fovea the area of sharpest vision.

peripheral vision

provided by the rods and cones outside the macula

vitreous humor

s a transparent jelly, helps maintain the shape of the eyeball.

aqueous humor

produced in the posterior chamber as a filtrate from plasma. It passes through the pupil into the anterior chamber where it is continually reabsorbed into a vascular space called the scleral venous sinus. removes waste products and helps maintain the internal chemical environment of the eye.

emmetropia

normal vision. The light rays then hit the lens, are bent again, and, in normal vision, the image is focused sharply on the retina

aqueous humor

watery liquid in the anterior and posterior chambers of the eye

chiasm/ chiasma

X-shaped crossing of the two optic nerves at the base of the brain

choroid

region of the retina and uvea

fovea centralis

small pit in the center of the macula that has the highest visual acuity

macula lutea

yellowish spot on the back of the retina; contains the fovea centralis

optic

pertaining to vision or the eye

optical

pertaining to vision or the eye

photoreceptor

a photoreceptor cell receives light and converts it into electrical impulses

tract

bundle of nerve fibers with a common origin and destination

uvea

middle coat of eyeball; includes iris, ciliary body, and choroid.

visual acuity

sharpness and clearness of vision

vitreous humor

a gelatinous liquid in the posterior cavity of the eyeball with the appearance of glass

Eyelid edema

can be a result of eyelid disorders (e.g., stye and chalazion), or is often produced by an allergic reaction due to cosmetics, pollen in the air, or stings and bites from insects. It can also be caused by conjunctivitis or dacryostenosis.

Ptosis

occurs when the upper eyelid is constantly drooped over the eye due to paresis (partial paralysis) of the muscle that raises the upper lid. It can be associated with diabetes, myasthenia gravis, brain tumor, and muscular dystrophy, all of which are described in previous subsequent chapters.

blepharoptosis

used for sagging of the eyelids due to excess skin.

Blepharitis

occurs when multiple eyelash follicles and tarsal glands become infected. The margin of the eyelid shows persistent redness and crusting and may become ulcerated. The infection is usually staphylococcal

chalazion

a small, painless, localized, whitish swelling inside the lid when a tarsal gland becomes blocked. It usually disappears spontaneously.

Stye/ Hordeolum

an infection of an eyelash follicle producing an abscess, with localized pain, swelling, redness, and pus formation at the edge of the eyelid.

Conjunctivitis

inflammation of the conjunctiva. has several causes. Viral and bacterial are contagious

Viral conjunctivitis

commonly caused by viruses that cause the common cold

bacterial conjunctivitis

frequently due to staphylococcal or streptococcal bacteria; may be caused by rubbing eyes, sharing makeup that is not your own.

allergic conjunctivitis

can be part of seasonal hay fever or be produced by year-round allergens such as animal dander and dust mites

irritant conjunctivitis

can be caused by air pollutants (smoke and fumes) and be chemicals such as chlorine and those found in soaps and cosmetics

neonatal conjunctivitis / ophthalmia neonatorum

can be caused by a blocked tear duct in the baby, by the antibiotic eyedrops given routinely at birth, or by sexually transmitted bacteria in an infected mother’s birth canal.

Dry eyes

are a common and chronic condition which over 75 million Americans suffer from. It is due to the tears losing water and becoming too salty so that the eyes sting and burn and vision becomes blurry

Dacryostenosis

a blockage of the drainage of tears, usually due to narrowing of the nasolacrimal ducts. Approximately 6% of newborns have this condition, but it may not be noticeable at birth because infants do not produce tears until they are several weeks old. Fortunately, nearly all blocked ducts open by the age of one year and do not require surgical opening.

Dacryocystitis

is an infection of the lacrimal sac, with swelling and pus at the medial corner of the eye.

Strabismus

“squinting,” is the loss of alignment of the eyes due to muscle control

Exotropia

an outward turning of one eye.

Esotropia

“crossed eyes,” is the eye turned in toward the nose (Figure 16.10). In congenital or infantile esotropia, both eyes look in toward the nose—the right eye looks to the left, and the left eye looks to the right.

Accommodative esotropia

is caused by uncorrected hyperopia (a refractive disorder). An eye will cross when attempting to keep a distant object in focus

accommodate

to adjust something to make it fit its needs.

accommodation

the act of adjusting something to make it fit the needs

accommodative

willing to adjust to create agreement

blepharitis

inflammation of the eyelid

blepharoptosis

drooping of the upper eyelid

chalazion

cyst on the outer edge of an eyelid caused by a blocked tarsal gland

contagious

able to be transmitted, as infections transmitted from person to person, from person to air, or from surface to person

dacyrocystitis

inflammation of the lacrimal sac

dacryostenosis

narrowing of the nasolacrimal duct

esotropia

a turning of the eye inward toward the nose

exotropia

a turning of the eye outward away from the nose

hordeolum/ stye

abscess in an eyelash follicle

infectious

capable of being transmitted, or caused by infection by a microorganism

ophthalmia neonatorum

conjunctivitis of the newborn