Eye Care Glossary

These are some terms that may be helpful to know. They pertain to ophthalmologists, opticians, optometrists and all things dealing with the anatomy and health of the eye.

age-related macular degeneration: (AMD, ARMD) (MAK-yu-lur). 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 (neovascularization), further disturbing macular function. Most common cause of decreased vision after age 60.

amblyopia: (am-blee-OH-pee-uh), “lazy eye.” Decreased vision in one or both eyes without detectable anatomic damage to the retina or visual pathways. Usually uncorrectable by eyeglasses or contact lenses.

astigmatism: (uh-STIG-muh-tiz-um) Refractive error. Optical defect in which refractive power is not uniform in all directions (meridians). Light rays entering the eye are bent unequally by different meridians, which prevents formation of a sharp image focus on the retina. Slight uncorrected astigmatism may not cause symptoms, but a large amount may result in significant blurring and headache.

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

cataract: Opacity or cloudiness of the crystalline lens, which may prevent a clear image from forming on the retina. Surgical removal of the lens may be necessary if visual loss becomes significant, with lost optical power replaced with an intraocular lens, contact lens, or aphakic spectacles. May be congenital or caused by trauma, disease, or age.

cataract extraction: Removal of a cloudy lens from the eye. An extracapsular cataract extraction leaves the rear lens capsule intact; with an intracapsular extraction there is complete removal of lens with its capsule, usually by cryoextraction.

conjunctiva: (kahn-junk-TI-vuh) Transparent mucous membrane covering the outer surface of the eyeball except the cornea, and lining the inner surfaces of the eyelids.

conjunctivitis: (kun-junk-tih-VI-tis), “pink eye. ” Inflammation of the conjunctiva. Characterized by discharge, grittiness, redness and swelling. Usually viral in origin, but may be bacterial or allergic; may be contagious.

convergence: Inward movement of both eyes toward each other, usually in an effort to maintain single binocular vision as an object approaches.

cornea: (KOR-nee-uh) Transparent front part of the eye that covers the iris, pupil, and anterior chamber and provides most of an eye’s optical power.

diabetic retinopathy: (ret-in-AHP-uh-thee). Spectrum of retinal changes accompanying long-standing diabetes mellitus. Early stage is background retinopathy. May advance to proliferative retinopathy, which includes the growth of abnormal new blood vessels (neovascularization) and fibrous tissue.

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 (mydriatics, cycloplegics) or result from blunt trauma.

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

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

fluorescein angiography: (FLOR-uh-seen an-jee-AH-gruh-fee) Technique used for visualizing and recording location and size of blood vessels and any eye problems affecting them; fluorescein dye is injected into an arm vein, then rapid, sequential photographs are taken of the eye as the dye circulates.

glaucoma: (glaw-KOH-muh) Group of diseases usually characterized by increased intraocular pressure resulting in damage to the optic nerve and retinal nerve fibers. A common cause of preventable vision loss. May be treated by prescription drugs or surgery.

hyperopia:  (hi-pur-OH-pee-uh), farsightedness. Refractive error. Focusing defect in which an eye is underpowered; light rays coming from a distant object strike the retina before coming to 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 (accommodation)

IOL: (intraocular lens) Plastic lens that may be surgically implanted to replace the eye’s natural lens.

intraocular pressure:  1. Fluid pressure inside the eye. 2. The assessment of pressure inside the eye with a tonometer. Also called tension.

iris:  Pigmented tissue lying behind the cornea that gives color to the eye (e.g., blue eyes) and controls amount of light entering the eye by varying the size of the pupillary opening.

laser:  Acronym: Light Amplification by Stimulated Emission of Radiation. High energy light source that uses light emitted by the natural vibrations of atoms (of a gas or solid material) to cut, burn or dissolve tissues for various clinical purposes: in the retina, to treat diabetic retinopathy and macular degeneration, to destroy leaking and new blood vessels (neovascularization); on the iris or trabecular meshwork, to decrease pressure in glaucoma; after extracapsular cataract extraction, to open the posterior lens capsule.

LASIK: (LAY-sik) Acronym: LAser in SItu Keratomileusis. Type of refractive surgery in 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: crystalline lens. The eye’s natural lens. Transparent, biconvex intraocular tissue that helps bring rays of light to a focus on the retina.

low vision: Term usually used to indicate vision of less than 20/200.

macula: Small central area of the retina surrounding the fovea; area of acute central vision.

myopia: (mi-OH-pee-uh), 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.

ophthalmologist: (ahf-thal-MAH-loh-jist) Physician (MD) specializing in diagnosis and treatment of refractive, medical and surgical problems related to eye diseases and disorders.

optic disc: optic nerve head. Ocular end of the optic nerve. Denotes the exit of retinal nerve fibers from the eye and entrance of blood vessels to the eye.

optician: (ahp-TISH-un) Professional who makes and adjusts optical aids, e.g., eyeglass lenses, from refraction prescriptions supplied by an opthalmologist or optometrist.

optic nerve: Largest sensory nerve of the eye; carries impulses for sight from the retina to the brain.

optometrist: (ahp-TAHM-uh-trist). Doctor of 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.

peripheral vision: Side vision; vision elicited by stimuli falling on retinal areas distant from the macula.

ptosis: (TOH-sis) Drooping of upper eyelid. May be congenital or caused by paralysis or weakness of the 3rd cranial nerve or sympathetic nerves, or by excessive weight of the upper lids.

pupil: Variable-sized black circular opening in the center of the iris that regulates the amount of light that enters the eye.

refractive error: Optical defect in an unaccommodating eye; parallel light rays are not brought to a sharp focus precisely on the retina, producing a blurred retinal image. Can be corrected by eyeglasses, contact lenses, or refractive surgery.

retina: (RET-ih-nuh) Light sensitive nerve tissue in the eye that converts images from the eye’s optical system into electrical impulses that are sent along the optic nerve to the brain, to interpret as vision. Forms a thin membranous lining of the rear two-thirds of the globe.

Snellen chart: Test chart used for assessing visual acuity. Contains rows of letters, numbers, or symbols in standardized graded sizes, with a designated distance at which each row should be legible to a normal eye. Usually tested at 20 ft.

strabismus: (struh-BIZ-mus). Eye misalignment caused by extraocular muscle imbalance: one fovea is not directed at the same object as the other.

20/20: Normal visual acuity. Upper number is the standard distance (20 ft.) between an eye being tested and the eye chart; lower number indicates that the tested eye can see the same small standard-sized letters or symbols as a normal eye at 20 feet.

visual acuity:  Assessment of the eye’s ability to distinguish object details and shape, using the smallest identifiable object that can be seen at a specified distance (usually 20 ft. or 16 in.)