Chapter 15 Anatomy
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.
