Glossary

A

accommodation - the ability of the eye to focus.

age-related macular degeneration (AMD, ARMD) - group of conditions that include deterioration of the macula, resulting in loss of sharp central vision. Two general types: "dry", which is more common, and "wet", in which abnormal new blood vessels grow under the retina and leak fluid and blood, further disturbing macular function. Most common cause of decreased vision after age 60.

amblyopia - sometimes called "lazy eye." Decreased vision in one or both eyes without detectable anatomic damage to the retina or visual pathways.

Amsler grid - a chart featuring horizontal and vertical lines used to test vision.

anterior chamber - fluid filled space inside the eye between the iris and the innermost corneal surface.

astigmatism - a vision problem that results in blurred images.

atrophy - wasting away. Decrease in size.

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B

bifocals - eyeglasses that incorporate two different powers in each lens, usually for near and distance corrections.

binocular vision - the ability to use both eyes at once.

blepharitis - inflammation of the eyelids, usually with redness, swelling, and itching.

C

cataract - a change in the structure of the crystalline lens that causes blurred vision.

choroid - the thin, blood-rich membrane that covers the white of the eyeball; responsible fore supplying blood to the retina.

ciliary body - the part of the eye that produces aqueous humor.

color blindness - reduced ability to discriminate between colors, especially shades of red and green.

conjunctiva - the membrane that lines the exposed eyeball and the inside of the eyelid.

conjunctivitis - inflammation of the conjunctiva of the eye.

cornea - the clear, dome-shaped surface that covers the front of the eye.

corneal curvature - the shape of the front surface of the eye.

cross eyes - see esotropia

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D

depth perception - the ability to distinguish objects in a visual field.

diabetic retinopathy - spectrum of retinal changes accompanying long standing diabetes mellitus.

dilated pupil - enlarged pupil, resulting from contraction of the dilator muscle or relaxation of the iris sphincter. Occurs normally in dim illumination, or may be produced by certain drugs, or result from blunt trauma.

diopter - unit to designate the refractive power of lens.

diplopia - double vision. Perception of two images from one object; images may be horizontal, vertical or diagonal.

dry eye syndrome - corneal and conjunctival dryness due to deficient tear production, predominately in menopausal women. Can cause foreign body sensation, burning eyes, filamentary keratitis, and erosion of conjunctival and corneal epithelium.

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E

endophthalmitis - pathologic condition. Inflamation of tissues inside the eyeball. Usually refers to purulent intraocular infection.

esotropia - cross eyes. Eye misalignment in which one eye deviates inward (toward the nose) while the other fixates normally.

excimer laser - class of ultraviolet lasers that removes tissue accurately without heating it. In refractive corneal surgery, controlled by computer to make precise preprogrammed shavings of eye tissue to produce a given optical correction. Used for photorefractive keratectomy (PRK); combined with automated lamellar keratoplasty (ALK) to produce LASIK.

exotropia - wall-eyes. Eye misalignment in which one eye deviates outward (away from the nose) while the other fixates normally.

exudative - oozing or casting off of fluids.

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F

farsightedness - see hyperopia

floaters - particles that float in the vitreous and cast shadows on the retina; seen as spots, cobwebs, spider, etc. Occurs normally with aging or with vitreous detachment, retinal tears, or inflammation.

G

glaucoma - increased intraocular pressure that can result in optic nerve damage and loss of sight.

H

hyaloid canal - narrow passageway that allows blood to flow through the eye.

hyperopia - farsightedness. Focusing defect in which an eye is underpowered; light rays coming from a distant object strike the retina before coming into sharp focus; blurring vision. Farsighted people expend focusing effort to see clearly in the distance, and close-up vision is blurred because it takes even more focusing effort. Corrected with additional optical power, which may be supplied by a plus lens (spectacle or contact) or by excessive use of the eye's own focusing ability.

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I

IOL (intraocular lens) - plastic lens that may be surgically implanted to replace the eye's natural lens.

iris - the colored part of the eye.

K

keratitis - inflammation of the cornea.

keratoconus - uncommon condition in which the cornea becomes thin and protrudes. Keratoconus literally means a cone-shaped cornea. This abnormal shape can cause serious distortion of vision.

L

LASIK - acronym: Laser in Situ Keratomileusis. Type of refractive surgery on which the cornea is reshaped to change its optical power. A disc of cornea is raised as a flap, then an excimer laser is used to reshape the intrastromal bed, producing surgical flattening of the cornea. Used for correcting myopia, hyperopia, and astigmatism.

lens (also called crystalline lens) - the transparent structure inside the eye that focuses light rays onto the retina.

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M

macugen - (pegaptanib sodium injection) is indicated for the treatemnet of neovascular (wet) age-related macular degeneration.

macula - the portion of the eye that allows us to see fine details clearly.

macular degeneration - degeneration in the macular region of the retina that results in decreased central vision and sometimes, in blindness.

myopia - nearsightedness. Focusing defect in which the eye is overpowered. Light rays coming from a distant object are brought to focus before reaching the retina. Requires a minus lens correction to "weaken" the eye optically and permit clear distance vision.

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N

near point of accommodation - the closest point in front of the eyes that an object may be clearly focused.

near point of convergence - the maximum extent the two eyes can be turned inward.

nearsightedness - see myopia

O

ocular hypertension - high (greater than 21 mm Hg) intraocular pressure.

ophthalmologist - physician (MD) specializing in diagnosis and treatment of refractive, medical and surgical problems related to eye disorders.

ophthalmoscopy - examination of the internal structure of the eye.

optic nerve - a bundle of more than 1 million nerve fibers that connects the retina with the brain. The optic nerve is responsible for interpreting the impulses it receives into images.

optician - professional who makes and adjusts optical aids, e.g., eyeglass lenses, from refraction prescriptions supplied by an ophthalmologist or optometrist.

optometrist - doctor op optometry (OD) specializing in vision problems, treating vision conditions with spectacles, contact lenses, low vision aids and vision therapy, and prescribing medications for certain eye diseases.

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P

pathologic - altered or caused by disease or abnormal function.

peripheral vision - side vision; vision elicited by stimuli falling on retinal areas distant to from the macula.

photophobia - sensitivity to light.

photodynamic therapy (PDT) - a platform technology that utilizes light-activated drugs to treat a wide range of medical conditions.

photorefractive keratectomy (PRK) - surgical procedure using an excimer laser to change the shape of the cornea.

pingecula - irritation caused by the degeneration of the conjunctiva.

pink eye - see conjunctivitis

posterior chamber - the back section of the eye's interior.

posterior optical segment - portion of the eye located behind the crystalline lens, and including vitreous, choroid retina, and optic nerve.

posterior vitreous detachment (PVD) - the separation of the vitreous from the retina.

presbyopia - a form of farsightedness in which it is difficult to focus on close objects or to read.

pupil - the dark center in the middle of the iris through which light passes to the back of the eye.

purulent - containing or consisting of pus.

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R

radial keratotomy - a surgical procedure in which incisions are made into the epithelium of the cornea to correct refractive error.

refraction - test. Determination of an eye's refractive error and the best corrective lenses to be prescribed. Series of lenses in graded powers are presented to determine which provide sharpest, clearest vision.

refractive error - the degree to which light reaches the back of the eye -- myopia, hyperopia, astigmatism.

retina - the light-sensitive nerve layer that lines the back of the eye. The retina sense light and creates impulses that are sent through the optic nerve to the brain.

retinal detachment - separation of the retina from the epithelium layer and from blood supply.

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S

sclera - the white visible portion of the eyeball. The muscles that move the eyeball are attached to the sclera.

scotoma - an area of partial or complete loss of vision surrounded by an area of normal vision.

slit lamp - microscope used for examining the eye; allows cornea, lens and otherwise clear fluids and membranes to be seen in layer-by-layer detail.

stereopsis - ability to perceive three-dimensional depth.

sty, stye - acute pustular infection of the oil glands of Zeis, located in an eyelash follicle at the eyelid margin.

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T

tonometry - test to measure intraocular pressure for glaucoma.

trifocal - eyeglass lens that incorporates three lenses of different powers. The main portion is usually focused for distance (20 ft.), the center segment for about 2 ft., and the lower segment for near (14in.).

20/20 - normal visual acuity. Upper number indicates that a patient can see standardized symbols on a chart 20 ft. away; lower number indicates that the same symbols can be seen at 20 ft. by an eye with normal optical system.

U

uvea - pigmented layers of the eye (iris, ciliary body, choroid) that contain most of the intraocular blood vessels.

V

visual acuity - the space visible to an eye in a given position of gaze.

visudyne® - (verteporfin for injection) is the first drug therapy for patients with age-related macular degeneration with predominantly classic subfoveal choroidal neovascularization (CNV).

vitreous body - a clear, jelly-like substance that fills the center of the eye.

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W

wall eyes - see extropia

Y

YAG laser - laser that produces short pulsed, high energy light beam to cut perforate, or fragment tissue.

J, Q, X, Y

There are no terms listed under these letters.

This information is not intended to be a substitute for individual medical advice in diagnosing or treating a health problem. Please consult with your health care provider about your health care concerns. If you would like to make an appointment with a Southwestern Eye Center doctor, please call 1-888-744-4400.

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