Test 3 Flashcards
accommodation
adjustment of the eye for various distances through modification of the lens curvature
aniscoria
inequality of the diameter of the pupils; may be normal or congenital. often normal if inequality is within 1 mm
aphakia
a condition in which part or all of the crystalline lens of the eye is absent, usually because of surgical removal for the treatment of cataracts
aqueous humor
a watery transparent liquid containing trace albumin and small amount of salts produced by the iris, ciliary body, and cornea
corneal arcus
opaque white ring about corneal periphery, seen in many individuals older than 60 years of age. this is due to deposit of lipids in the cornea of to hyaline degeneration. may indicate a lipid disorder, most commonly type II hyperlipidemia if present before the 40 years of age (seen in younger people is called arcus juvenilis)
astigmatism
an abnormal condition in which the light rays cannot be focused clearly in a point on the retina because of an irregular curvature of the cornea or lens
cataracts
opacity of the lens; most commonly resulting from denaturation of the lens protein caused by aging.
chalazion
small, hard tumor analogous to sebaceous cyst developing on the eye lids, formed by the distention of a meibomian gland with secretion.
choroid
the middle vascular tunic of the eye lying between the retina and the sclera. Dark brown vascular coat of the eye between the sclera and retina, extending from ora serrata to optic nerve. Consists of blood vessels united by connective tissue containing pigmented cells and is made up of five layers.
ciliary body
the thickened part of the vascular tunic of the eye that joins the iris with the anterior portion of the choroid. Consist of three zones: ciliary disk, ciliary crown, and ciliary muscle.
cones
the photosensitive, outward-directed, conical process of a cone cell essential for sharp vision and color vision; cones are the only photoreceptor in the fovea centralis and become interspersed with increasing numbers of rods toward the periphery of the retina.
conjunctiva
the mucous membrane investing the anterior surface of the eyeball and the posterior surface of the lids.
conjunctivitis
inflammation of the conjunctiva caused by infectious agents or by allergies; commonly called pinkeye.
cornea
the clear, transparent anterior portion of the fibrous coat of the eye comprising about one sixth of its surface. It is the chief refractory structure of the eye.
depth perception
perception of spatial relationships; three dimensional perception. The visual ability to judge depth or distance.
diabetic retinopathy (history)
a condition characterized by dot hemorrhages or microaneurysms and the presence of hard and soft exudates.
diabetic retinopathy (proliferation)
a condition characterized by development of new vessels as a result of anoxic stimulation; vessels grow out of the retina toward the vitreous humor.
diopeter
refractive power of the lens with focal distance of 1 meter, used as unit of measurement in refraction.
diplopia
the condition in which a single object is perceived as two objects (double vision).
drusen
tiny yellow or white deposits in the retina of the eye or on the optic nerve head.
ectropion
eversion (outward rolling) of an edge or margin; as the edge of the eyelid.
entropion
inversion (inward rolling) of an edge or margin; especially the margin of the lower eyelid.
exophthalmos
an increase in the volume of the orbital content, causing a protrusion of the globes forward. It may be bilateral or unilateral. The most common cause of bilateral is Graves’ disease (thyroid disease), but when unilateral protrusion is noted a retro-orbital tumor must be suspected.
farsightedness
an error of refraction in which, with accommodation completely relaxed, parallel rays come to focus behind the retina.
glaucoma
a disease of the optic nerve wherein the nerve cells die, producing increased cupping appearance of the optic nerve. An abnormal condition of elevated pressure within an eye resulting from obstruction of the outflow of aqueous humor. Produces defects in the visual field and may result in blindness.
hemianopia
blindness for half the field of vision in one or both eyes.
hordeolum (sty)
a suppurative inflammation of a sebaceous gland of the eyelid.
hyperopia (farsightedness)
a refractive error in which light rays entering the eye are focused behind the retina.
hyphema
blood in the anterior chamber of the eye in front of the iris.
iris
the colored contractile membrane suspended between the lens and cornea in the aqueous humor of the eye, separating the anterior and posterior chambers of the eyeball and perforated in the center by the pupil. By contraction and dilatation it regulates the entrance of light.
iritis
inflammation of the iris.
legal blindness
in the United States, a person is usually considered legally blind when vision in the better eye, corrected by glasses, is 20/200 or less, or in the case of a constricted field of vision: 20 degrees or less in the better eye.
miosis
abnormal contraction of pupils.
myopia (nearsightedness)
a condition resulting from a refractive error in which light rays entering the eye are brought into focus in front of the retina.
night blindness
decreased ability to see in reduced illumination. Seen in patients with impaired rod function; often associated with a deficiency of vitamin A.
nystagmus
involuntary rhythmic movements of the eyes; the oscillations may be horizontal, vertical, rotary, or mixed.