Chapter 15 Anatomy

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Emmetropia

). The condition in which the lens is flattened so that nearly parallel rays from a distant object are focused on the retina is referred to as _______ and is the normal resting condition of the lens.

lasix

An alternative procedure is _____, or laser corneal sculpturing, in which a thin portion of the cornea is etched away to make the cornea less convex.

conjunctivitis

Inflammation of conjunctiva, usually from bacterial infection; one form, pinkeye, occurs primarily in children

cornea

The ____ is transparent

accommodation

The process of changing the shape of the lens is referred to as ______

The lacrimal apparatus

consists of a lacrimal gland situated in the superolateral corner of the orbit and a nasolacrimal duct beginning in the inferomedial corner of the orbit

bifocals

glasses that have different lens on the top and bottom

progressive lenses

glasses that have graded lens

aqueous humor

helps maintain intraocular pressure

The eye

includes the eyeball (the globe of the eye) and the lens

Color blindness

results from the dysfunction of one or more of the three photopigments involved in color vision.

radial keratotomy

technique for correcting myopia is ______, which consists of making a series of four to eight radiating cuts in the cornea.

scleral venous sinus

venous ring at the base of the cornea called the ________

focal point

As light rays converge, they finally reach a point at which they cross. this is called what

cataract

Clouding of lens as a result of advancing age, infection, or trauma; most common cause of blindness in the world

color blindness

Complete or partial absence of perception of one or more colors; most forms are more frequent in males

astigmatism

Cornea or lens is not uniformly curved, so image is not sharply focused

presbyopia

Decrease in near vision, a normal part of aging

diplopia

Double vision

hyperopia

Farsightedness—ability to see distant but not close objects; caused when cornea is too flat or lens has too little refractive power relative to length of eye

lateral rectus muscles

Four of these muscles run more or less straight anteroposteriorly: the superior, inferior, medial, and _______.

reflection

If light rays strike an object that is not transparent, they bounce off the surface. this is called

dichromatism

If one pigment is dysfunctional and the other two are functional, the condition is called _______.

Fovea Centralis

In the center of the macula is a small pit, the _______.

extra note

Increased cerebrospinal fluid (CSF) pressure associated with hydrocephalus may cause the optic disc to swell, a condition referred to as papilledema (pă-pil-e-dē′mă). Furthermore, cataracts (opacity of the lens; see the Diseases and Disorders table, "Vision," later in this chapter) are usually discovered or confirmed by ophthalmoscopic examination.

stye

Infection of eyelash hair follicle

myopia

Nearsightedness—ability to see close but not distant objects; caused when refractive power of cornea and lens is too great relative to length of eye

Neonatal gonorrheal opthalmia

Neisseria gonorrhoeae infection in eyes of newborn infant whose mother has gonorrhea; can cause blindness if the infant is not treated with silver nitrate, tetracycline, or erythromycin drops soon after birth

strabismus

One or both eyes are misdirected; can result from weak eye muscles; lazy eye

acute contagious conjunctivitis

One type of conjunctivitis caused by a bacterium is _______, also called pinkeye.

hyperopia

People who have _______, or farsightedness, can see distant objects clearly, but close objects appear blurry.

myopia

People who have _______, or nearsightedness, can see close objects clearly, but distant objects appear blurry.

sclera

The _____ helps maintain the shape of the eyeball, protects its internal structures, and provides an attachment point for the muscles that move it.

Optic Disc

The _____ is a white spot just medial to the macula through which the central retinal artery enters and the central retinal vein exits the eyeball

lens

The _____ is an unusual biological structure. It is transparent and biconvex, with the greatest convexity on its posterior side.

sclera

The _____ is the firm, opaque, white, outer layer of the posterior five-sixths of the eyeball.

Eyebrows

The _____ prevent perspiration from running down the forehead and into the eyes and irritating them. _____ also help shade the eyes from direct sunlight.

fovea centralis

The ______ contains only cone cells, and the cells are more tightly packed there than any where else in the retina.

Macula

The ______ is a small yellow spot, approximately 4 mm in diameter, near the center of the posterior retina

cornea

The ______ is an avascular, transparent structure that permits light to enter the eye and bends, or refracts, that light as part of the eye's focusing system.

fovea centralis

The ______ is the region of the retina where light is most focused when the eye is looking directly at an object.

anterior chamber; posterior chamber

The ______ lies between the cornea and the iris, and the smaller _______ lies between the iris and the lens

Eyelids

The ______, or palpebrae (pal-pē′brē), with their associated lashes, protect the eyes from foreign objects.

neural

The _______, in turn, has several sublayers

Ciliary Body

The ________ is continuous with the choroid

light and dark adaptation

The adjustment of the eyes to changes in light, as occurs when going from a darkened building into the sunlight or vice versa, is called _________

Canthi

The angles where the eyelids join at the medial and lateral margins of the eye are called ______

suspensory ligaments

The ciliary body consists of an outer ciliary ring and an inner group of ciliary processes, which are attached to the lens by ________

ciliary muscles

The ciliary body contains smooth muscles called the _______

intrinsic eye muscles

The ciliary muscles, sphincter pupillae, and dilator pupillae are sometimes referred to as the ______

rhodopsin

The discs contain ______, a purple pigment that consists of the protein opsin covalently bound to a yellow photosensitive pigment called retinal (derived from vitamin A)

presbyopia

The increase in the near point of vision that develops with age is called _____.

Pupil

The iris is a contractile structure, consisting mainly of smooth muscle, surrounding an opening called the _____

Caruncle

The medial canthus contains a small, reddish-pink mound called the _____ (mound of tissue), which houses some modified sebaceous and sweat glands.

Punctum

The opening of each lacrimal canaliculus

fibrous tunic

The outer ________ consists of the sclera and cornea

far point of vision

The point at which the lens does not have to thicken for focusing to occur is called the ______ and is normally 20 feet or more from the eye.

near point of vision

The point at which this blurring occurs, called the _______, is usually 2-3 inches from the eye for children, 4-6 inches for a young adult, 20 inches for a 45-year-old adult, and 60 inches for an 80-year-old adult

Pigmented Layer; Neural Layer

The retina consists of the outer _____, which is composed of pigmented simple cuboidal epithelium, and the inner _____, which responds to light.

tunics

The wall of the eyeball is composed of three _______, or layers

sclera

The white of the eye

Vascular

The______ tunic contains a large number of melanin-containing pigment cells and appears black in color.

convergence

This medial rotation of the eyes, called ______, is accomplished by a reflex that stimulates the medial rectus muscle of each eye.

oblique muscles

Two other muscles, the superior and inferior _______, are positioned at an angle to the globe of the eye.

trachoma

Type of conjunctivitis caused by Chlamydia; leading cause of infectious blindness in the world; transmitted by contact or flies

The 6 Extrinsic Muscles

What causes the eye to move

Lacrimal Gland

What gland produces tears

Accessory Structures

What structures include the eyebrows, eyelids, eyelashes, conjunctiva, lacrimal apparatus, and extrinsic eye muscles

Vascular Tunic

What tunic contains most of the blood vessels in the eye

Rods

______ are bipolar photoreceptor cells that are involved in noncolor vision; they are responsible for vision under conditions of reduced light

Cones

______ are bipolar photoreceptor cells with a conical, light-sensitive part that tapers slightly from base to apex

Presbyopia

______ is the normal, presently unavoidable degeneration of the accommodation power of the eye associated with aging.

Eyelashes

_______ are attached as a double or triple row of hairs to the free edges of the eyelids.

Ciliary Glands

_______ are modified sweat glands that open into the follicles of the eyelashes to keep them lubricated.

A Sty

_______ forms when one of these glands becomes inflamed

Depth of Focus

_______ is the greatest distance through which an object (for example, a newspaper that you are reading) can be moved and still remain in focus on the retina

Visible Light

_______ is the portion of the electromagnetic spectrum that can be detected by the human eye and includes wavelengths between 380 and 750 nm.

Retinitis pigmentosa (RP)

_________ is an inherited disorder characterized by progressive degeneration of rod and/or cone cells in the retina, accompanied by accumulation of pigment islands in the retina

Meibomian glands

_________, or tarsal glands, are sebaceous glands near the inner margins of the eyelids

Astigmatism

a type of refractive error that affects the quality of focus.

glaucoma

abnormal increase in intraocular pressure, can result.

Refraction

bending of light

focusing

causing light to converge

Conjunctiva

is a thin, transparent mucous membrane.

Conjunctivitis

is an inflammation of the conjunctiva caused by an infection or other irritation.

the retina

is the nervous tunic of the eyeball

Sebum

lubricates the lids and restrains tears from flowing over the margin of the eyelids.

Hypertension

nicking in your eyes

retina

the _____ consists of a neural layer and a pigmented layer

Iris

the _____ is attached at its lateral margins to the ciliary body

Vascular

the ______ tunic consists of the ciliary body and the iris.

middle vascular tunic

the _______ consists of the choroid, ciliary body, and iris

Optic Disc

the blind spot

Iris

the colored part of the eye

Visual acuity

the eye's ability to focus an image on the retina so that a clear image is perceived.

nervous tunic

the inner _______ consists of the retina.

Accessory structures

these structures protect, lubricate, move, and in other ways aid the function of the eye.

vitreous humor

transparent, jellylike substance

cone-rod dystrophies

when the cone cells degenerate first

rod-cone dystrophies

when the rod cells degenerate first.


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