VOCAB FOR VISION CARE Flashcards
amblyopia
(lazy eye) decreased vision without detectable damage in the eye or visual pathways. Possible treatment, for children only, includes occlusion of the dominant eye or eyeglasses. If bifocals are prescribed, fit mid-pupil.
ametrophia
Any faulty refractive ability of the eye, such a hyperopia, myopia, or astigmatism.
Amplitude of accommodation (AA)
Maximum increase in optical power of an eye produced by a change in shape of its lens
Amsler grid
Graph paper like grid used in detecting central visual field distortions or defects (i.e. macular degeneration).
andirida
Absence, complete or partial, of the iris.
angle closure glaucoma
Sudden rise in intraocular pressure that occurs in patients with narrow anterior chamber angles. Aqueous fluid behind iris cannot pass through pupil and pushes iris forward, preventing aqueous drainage through the angle.
aniseikonia
A condition in which the ocular image of an object as seen by one eye differs so much in size or shape from that seen by the other eye that the two images cannot be fused into a single impression
anisocoria
unequal pupil size, when the difference is 1mm or more.
anisometropia
Unequal refractive errors in the two eyes; at least 1.00 D difference
anterior chamber
Area behind the cornea and in front of the lens and iris. It contains aqueous humor.
Anterior chamber angle
The junction of the cornea and the iris, from which aqueous humor leaves the eye (also called filtration angle) Includes the outermost part of the angle, the front of the ciliary body, the trabecular meshwork, and the Canal of Schlemm
anterior segment
Front third of the eyeball
anterior synechiae
Fibrous adhesions of the iris to the cornea or trabecular
Antimetropia
One eye is hyperopic and the other is myopic.
aphakia
An eye that has had the crystalline lens removed.
aqueous humor
The clear, watery fluid contained in the space between the cornea and iris of the eye. Flows between and nourishes the lens and cornea. The fluid is secreted by the ciliary processes.
arcus senilis
An opaque ring, gray to white in color, that surrounds the periphery of the cornea. there are no symptoms, does not disturb vision, and requires no treatment.
asthenopia
Eyestrain. When the eyes get tired from excessive or intense use. Symptoms may include pain in the eyes, headache, dimness of vision, etc…
astigmatism
Optical defect in which the refractive power is not the same in all meridians and must be corrected with cylinder or toric lenses. “With the rule” is the most common, this is when the minus axis meridian is at or near (within 30 degrees) the 0 to 180 meridian.
axial myopia
eyeball is too long
basement membrane
A thin sheet of extracellular substance to which the basal surfaces of membranous epithelial cells are attached; also called the basal lamina.
bilateral
Affecting or occurring on both sides.
binocular vision
The blending of the separate images seen by each eye into a single image going to the brain, allowing three dimensional images, which leads to depth perception.
bleb
a small blister like sac filled with a watery fluid
blepharitis
Inflammation of the lid margins
blindness
Usually defined as central visual acuity of 20/200 or less in the better eye after correction, or visual acuity better than 20/200 if there is a field defect in which the widest diameter of the visual field subtends an angle distance no greater than 20 degrees (some states include up to 30 degrees
blind spot
(1) A small area of the retina where the optic nerve enter the eye; occurs normally in all eyes. (2) Any gap in the visual field corresponding to an area of the retina where no visual cells are present; associated with eye disease.
Bowman’s membrane
One of the five layers that is located just under the epithelium and above the corneal stroma.
Canal of Schlemm
A circular canal situated at the juncture of the sclera and cornea through which the aqueous humor is excreted after it has circulated between the lens ands the iris and between the iris and the cornea.
canthus
The angle formed by the meeting of the upper and lower eyelids at either side of the eye.
cataract
Any opacity of the crystalline lens. As the cataract develops near acuity may improve due to the myopic shift. This is called “second sight.” The only treatment is surgery. Once the lens is removed it is known as aphakia. If the lens is replaced with an intraocular lens (IOL) it is called pseudophakia. Spectacle lens magnifies the aphakic image about 25%, contact lens magnifies about 7%.
chalazion
Small tumor of eyelid due to inflammatory enlargement of a Meibomian gland. (Stye)
chiasm
The point where the optic nerves from each eye are combined.
choroid
Layer behind retina that contains blood vessels and nourishes the retina.
cilia
eyelashes
ciliary body
Tissue inside the eye made up of ciliary muscles and ciliary processes.
ciliary processes
The projections of the ciliary body that secrete aqueous humor.
cilium
eyelashes
color blindness
Is the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions.
cones
Retinal cones are concerned with visual acuity and color discrimination.
conjunctiva
The thin membrane covering the anterior surface of the eyeball and lining the eyelids.
conjunctivitis
Inflammation of the conjunctiva. Also called “pink eye”
Conoid of sturm
a representation of how rays are refracted through two different powered meridians (eg: a sphero- cylindrical lens). So, instead of one focal point, they form two focal lines.
convergence
(1) An inward turning of the eyes as when looking at a near object. (2) The action of light rays traveling toward a real image point.
Cornea
Transparent front semant of the eye. Provides most of the eye reflective power (approx. 43 D). It is composed of 5 identifiable layers. From anterior to posterior: Epithelium, Bowman’s membrane, Stroma, Descemet’s membrane, and the Endothelium. The epithelium heals without scarring in 24-48 hours. bowman’s membrane scars if damaged. The stroma comprises 90% of the corneal bulk. The endothelium has little is any regenerative ability.
corneal abrasion
A scraped area of corneal surface with loss of superficial tissue (epithelium)
corneal ulcer
infection on the surface of the eye caused by injury dryness due to lack of tear production, or infection.
Curvature myopia
the eye is normal size but the curvatures of the lens and cornea are increased (steeper)
cycloplegics
A transparent biconvex lens structure located between the iris and vitreous. It is attached to the ciliary processes and to the posterior portion of the ciliary body by means of fine suspensory ligaments referred to as the zonular fibers. It protects the retina from UVA by absorbing ultraviolet light between 310 and 410 nm. Index of refraction 1.398.
dacryocystitis
Inflammation of the lacrimal sac
Decemet’s membrane
Thin, elastic layer deep in the cornea formed by the endothelium and composed of collagen and elastic fibrils.
depth perception
Ability to perceive the solidity of objects and their relative position in space; also called stereoscopic vision.
deviation
Misalignment of eyes caused by muscle imbalance.
diabetic retinopathy
A spectrum of retinal changes accompanying long-standing diabetes mellitus.
dialator papillae
The iris muscle
diopter
A measurement of the degree to which light converges or diverges; also of lens refractive power. Equal to the reciprocal of the focal length of a lens (in meters), e.g., a 2-diopter lens brings parallel rays of light to a focus at half a meter.
diplopia
Seeing one object as two
divergence
The outward rotation of the two eyes to see in the distance
ectropion
where the lower eyelid droops away from the eye and turns outwards
edema
Excessive accumulation of fluid in the tissue spaces, due to disturbance in the mechanism of fluid exchange.
emmetropia
When distance objects are focused on the retina by an eye with relaxed accommodation
endothelium
A monolayer of specialized, flattened cells that line the posteri or surface of the cornea
entropion
An inward turning of the margin of an eyelid.
enucleation
Complete surgical removal of the eyeball (or tumor, or other body) without rupture
epithelium
The epithelial tissue that covers the front of the cornea
esophoria
A tendency of one eye to deviate towards the nose. Can be overcome by fusion
esotropia
(Crossed eyes) A manifest deviation of one eye towards the nose. Cannot be overcome by fusion.
evisceration
An operation that removes the contents of the eyeball
exophoria
A tendency of one eye to deviate outward from the nose
exotropia
(Wall eyed) A manifest deviation of one eye outward from the nose.
extrinsic muscles
The six muscles of the eyeball; medial and lateral recti, superior and inferior recti, and superior and inferior oblique.
eye
The organ of vision as a whole. It is made up of three tunics or coats, (1) The fibrous tunic (sclera and cornea). (2) The vascular tunic (choroid, ciliary body, and the iris). (3) The nervous tunic (optic nerve and its outspreading into the retina).
eyelids
Structures covering the front of the eye that serve to protect it and limit the amount of light entering the pupil. Also distribute the tear film over the exposed corneal surface.
far point
The location of the farthest object on which the fully relaxed eye can focus. For a normal eye, the far point is located at infinity.
farsighted
hyperopia
field of vision
That area that can be seen without shifting the eye.