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-AK (Astigmatic Keratotomy) Procedure in which a surgeon cuts the cornea so that it is more spherical when it heals, thus reducing astigmatism.
-AMD or ARMD (age-related macular degeneration) Disorder characterized by the gradual loss of central vision due to a damaged macula (which is made up of retinal cones necessary for sight).
-Allergy Sensitivity to a substance, accompanied by sneezing, itching, watery eyes, difficulty breathing or rashes.
-Amblyopia Also called lazy eye. Diminished sight in one eye.
-ANSI Z87.1 The American National Standards Institute's Practice for Occupational and Educational Eye and Face Protection; eyewear that meets this standard is considered safer than eyewear that does not.
-Anterior chamber Part of the eye behind the cornea and in front of the iris and lens.
-Antioxidant Substance that inhibits oxidation and can guard the body from the damaging effects of free radicals. Molecules with one or more unpaired electrons, free radicals can destroy cells and play a role in many diseases. Antioxidants may help prevent macular degeneration and other serious eye diseases.
antireflective coating (AR coating) Thin layer(s) applied to a lens to reduce the amount of reflected light and glare that reaches
the eye.
-Aqueous humor Clear fluid in the eye that both provides nutrients and determines intraocular pressure.
-Astigmatism Condition caused by an irregularly shaped cornea, resulting in two focal points (blurred vision).
-Bifocal Having one segment for near vision and one segment for far vision.
-Bowman's membrane Corneal layer between the epithelium and the stroma.
-Bridge The part of eyeglasses that extends across the nose.
-Cable temple Style of glasses that wraps around the ear, to keep them well-fastened.
-Cataract Clouding of the natural lens of the eye, resulting in impaired vision. Cataract surgery involves removing the eye's natural lens, and replacing it with an artificial one.
-Choroid Layer of blood vessels and pigments (usually brown or blue) that lies beneath the sclera (the white of the eye). Often mistakenly called the iris.
-Ciliary body Part of the eye that contains a focusing muscle and connective tissue.
-CMV retinitis (cytomegalovirus retinitis) Serious eye infection usually found in those with immune problems, such as AIDS patients; symptoms include floaters, blind spots, blurry vision and vision loss.
-Collagen Fibrous protein in bones and connective tissue, it is also present in the eye. One type of vision correction surgery now under FDA review heats collagen around the edges of the cornea (which lets light into the eye). This procedure reshapes the cornea, helping it focus light right onto the retina, for clearer vision.
-Color blindness Partial or total inability to distinguish specific colors.
-Computer Vision Syndrome Condition caused by prolonged computer use, and characterized by eyestrain, blurred vision, headaches and dry or irritated eyes.
-Cone A photosensitive receptor in the retina that helps you to see color.
-Conjunctiva Mucous membrane that lines the visible part of the eye and the inner surface of the eyelid.
-Conjunctivitis Inflammation of the conjunctiva.
-Contact lens drops Eye drops for contact lens wearers; regular eye drops can discolor contact lenses.
-Contrast sensitivity The least amount of contrast that you can still see.
-Cornea The clear part of the eye covering the iris and pupil; it lets light into the eye, permitting sight.
-Corneal abrasion A tearing or puncture of the cornea.
-Corneal implants Devices (such as rings or contacts) placed in the eye, usually to correct vision.
-Corneal ring Type of vision correction surgery where a doctor inserts a tiny plastic ring into the cornea (which lets light into the eye). This ring reshapes the cornea, helping it to focus light better onto the retina so you can see better. The ring can be adjusted and even removed if desired.
-Corneal ulcer Wound in the surface of the eye caused by injury, dryness due to lack of tear production, or infection.
-Crossed eyes Type of strabismus (a misalignment of the eyes) where one or both eyes point inward, toward the nose.
-Dacryostenosis Blocked tear duct, which is characterized by a lot of tearing.
-Daily wear These soft contact lenses are worn every day for six months up to one year. They require daily cleaning and disinfecting, as well as a periodic enzymatic soak (usually once a week).
-Descemet's membrane Corneal layer between the stroma and the endothelium.
-Diabetic Retinopathy Leaking of retinal blood vessels in advanced or long-term diabetes, affecting the macula or retina. Vision can be
seriously distorted or blurred.
-Diopter Unit which measures the refractive (light-bending) power of a lens; eyecare practitioners use it in eyeglass and contact lens prescriptions. A negative number refers to nearsightedness, while a positive number refers to farsightedness. For example, someone with -8.00 diopter lenses is very nearsighted, while someone with +0.75 diopter lenses is only slightly farsighted.
-Disposable contact lenses Technically, this is any contact lens that is thrown away after a short period of time. Among most eyecare practitioners, "disposable" usage ranges from one day to two weeks, while "frequent replacement" lenses are discarded monthly or quarterly.
-Drooping eyelids Also called ptosis. Condition in which the upper eyelid(s) only sag. It can be present at birth or caused by a later problem with the muscles lifting the eyelid, called levators.
-Dry eye Lack of sufficient lubrication and moisture in the eye. Most dry eye complaints are temporary and easily relieved; dry eye syndrome is chronic and needs more advanced treatment by an eyecare practitioner.
-Endothelium The cornea's inner layer of cells.
-Enzymatic cleaner A cleaner that removes protein deposits and other debris from contact lenses. It's recommended for use either daily, weekly, or monthly. Some enzymatic cleaners are a small tablet dropped into a solution along with the lens; others come in liquid form.
-Epithelium The cornea's outer layer of cells.
-Extended wear Currently, these contact lenses are FDA-approved to be worn without removal for up to seven days, meaning some people will be comfortable sleeping with them in their eyes.
-Eyecare practitioner Optometrists (O.D.s) and ophthalmologists (M.D.s) both practice eyecare, but in different ways: O.D.s examine eyes to determine eyewear prescriptions and check for and treat many diseases such as glaucoma. M.D.s are medical doctors who treat disease and perform surgery. There is some overlap, as O.D.s can prescribe many medications, and M.D.s can dispense eyewear. Other non-doctor eyecare practitioners include paraoptometrics and contact lens technicians, who assist in patient care.
-Farsightedness Also called hyperopia. To farsighted people, near objects have a geater potenial to result in blurriness and or eyestrain, while far objects are less likely to result in these same symptoms.
-FDA (Food & Drug Administration) A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eye drops. In the U.S., these products must be approved by the FDA before they can be marketed.
-Floaters Small specks that pass across your field of vision, these are clumps of cells inside the transparent gel filling the eyeball in front of the retina.
-Fovea A depression in the retina that contains only cones (not rods), and that provides acute eyesight.
-Frequent replacement contact lenses Technically, this is any contact lens that is thrown away after a moderately short period of time. Among most eyecare practitioners, "disposable" usage ranges from one day to two weeks, while "frequent replacement" lenses are discarded monthly or quarterly.
-Glaucoma Disease characterized by excessive fluid (aqueous humor) in the eye, high intraocular pressure and vision impairment. Blindness can result.
-Graves' ophthalmopathy Thyroid-related, autoimmune eye disorder usually associated with Graves' disease; symptoms include eyelid retraction, bulging eyes, light sensitivity, discomfort, double vision and vision loss.
-Hard contact lenses Rarely worn now, these are the small, hard lenses made of PMMA material that many people wore in the '70s and '80s. Compared with modern soft and rigid lenses, they are less healthy to wear long-term, since the material doesn't allow oxygen to reach the surface of the eye.
-High index Type of lens with a higher index of refraction, meaning that light travels faster through the lens to reach the eye than with traditional glass or plastic. It is denser, so the same amount of visual correction occurs with less material (whether glass or plastic) -- so the lens can be thinner.
-Hyperopia Also called farsightedness. To people with hyperopia, near objects have a geater potenial to result in blurriness and or eyestrain, while far objects are less likely to result in these same symptoms.
-Intraocular pressure (IOP) Eye pressure, as determined by the amount of aqueous humor filling it. High IOP (ocular hypertension) can be a sign of glaucoma.
-Iris the colored portion of the eye that regulates the amount of light entering the eye by changing the size of the pupil.
-Keratectomy Surgical removal of part of the cornea.
-Keratoconus Condition in which the cornea develops a cone-shaped bulge that can result in major blurring and distortion.
-Keratoplasty Any of several types of corneal surgery, such as shrinking the collagen to reduce farsightedness or transplanting a new cornea to treat keratoconus.
-Keratotomy Incision of the cornea.
-Laser photocoagulation Procedure in which a surgeon uses a laser to coagulate tissue, usually to seal leaking blood vessels and destroy new ones in diseases like macular degeneration and diabetic retinopathy.
-LASIK (Laser-Assisted In Situ Keratomileusis) Surgical procedure in which a tiny flap is cut in the top of the cornea, this is done by the most accurate instrument of its kind - the Hansatome
-Lateral rectus muscle Muscle that moves the eye away from the nose.
-Lens The nearly spherical body in the eye that focuses light rays onto the retina.
-Limbus Boundary area connecting the cornea and sclera; the three form the eye's outermost layer.
-Lipid A fatlike substance that can collect on contact lenses, making them uncomfortable.
-Low vision Also called partial sight. Sight that cannot be satisfactorily corrected with glasses, contacts, or surgery. Low vision usually results from an eye disease such as glaucoma or macular degeneration. There are specialized optical and nonoptical devices that can enhance or improve visual ability in the low vision patient. The selection of the proper device to be used is determined in a special low vision eye examination.
-Lutein An antioxidant that is found throughout the body, but is concentrated in the macula. Lutein is believed to help protect the eyes from free radical damage caused by the sun's harmful rays.
-Macula Part of the eye near the middle of the retina.
-Medial rectus muscle Muscle that moves the eye toward the nose.
-Microcornea Abnormally small cornea.
-Microkeratome Engineered to the highest standards, this automated device allows a surgeon to make a "corneal flap" with absolute precision. Underlying corneal tissue is removed with an excimer laser, and the flap is put back in place. LASIK corrects myopia, hyperopia and astigmatism.
-Multifocal Type of spectacle or contact lens design that includes more than one focal area, such as bifocals or trifocals.
-Myopia Also called nearsightedness. Condition in which visual images come to a focus in front of the retina, resulting in blurred vision of distant objects.
-Nearsightedness Also called myopia. Condition in which visual images come to a focus in front of the retina, resulting in defective vision of distant objects.
-Ocular hypertension Condition in which the intraocular pressure of the eye is elevated above normal and which may lead to glaucoma.
-Ophthalmologist A medical doctor (M.D.) who specializes in the eye. Ophthalmologists perform eye exams, treat disease, prescribe medication, and perform surgery. They may also write prescriptions for eyeglasses and contact lenses.
-Optician Opticians are not doctors, but in some states they must complete training and be licensed. And in some states they can become certified, after special training, to fit contact lenses. Most opticians sell and fit eyeglasses, sunglasses, and specialty eyewear that are made to an optometrist's or ophthalmologist's prescription.
-Optic nerve Part of the eye that carries stimuli from the rods and cones to the brain.
-Optometrist Doctors of optometry (O.D.s) examine eyes for both vision and health problems, prescribe glasses, and fit contact lenses. They can prescribe many ophthalmic medications and may participate in your pre- and post-operative care if you have eye surgery. O.D.s must complete four years of post-graduate optometry school for their doctorate.
-Overconvergence Condition in which the eyes come too far inward when focusing on a near object, resulting in blurring.
-Peripheral vision The edges of your visual field.
-Photoablation Procedure in which a surgeon uses ultraviolet radiation to remove tissue.
-Photochromic Able to change lens color or darkness/density depending upon the degree of exposure to light.
-Photokeratitis "Sunburn" of the cornea; symptoms include discomfort, blurred vision, and light sensitivity. The temporary vision loss that can result is called "snow blindness."
-Pinguecula A yellowish, thickened lesion on the conjunctiva.
-Plano A term eyecare professionals use to describe lenses with no corrective power. The term is most often applied to nonprescription sunglasses or contact lenses that are worn for cosmetic purposes only.
-PMMA (polymethyl methacrylate) Old-fashioned hard contacts were made of PMMA, which is not oxygen permeable; today's rigid lenses contain other polymers that allow oxygen to reach your eye.
-Polarized lenses Lenses that block light reflected from horizontal surfaces such as water, to reduce glare.
-Polycarbonate Plastic that is very impact-resistant, and is thus sometimes used for spectacle lenses and frames.
-Posterior chamber Part of the eye behind the iris and in front of the lens.
-Presbyope Person who has difficulty reading print and seeing near objects.
-Presbyopia Inability of the eye lens to focus incoming light, resulting in blurred vision at a reading distance and eyestrain.
-Prescription lenses Lenses that provide vision correction as prescribed by an eyecare practitioner.
-Progressive lenses (also, progressive addition lenses or PALs) Multifocal lenses whose corrective powers change progressively throughout the lens. A wearer looks through one portion of the lens for distance vision, another for intermediate vision, and a third portion for reading or close work. Each area is blended invisibly into the next, without the lines that traditional bifocals or trifocals have.
-Propionate A soft, flexible material that is sometimes used in goggles.
-Protective eyewear Eyewear made with impact-resistant lenses, usually polycarbonate, that protects the eyes, especially in working situations or sports.
-Protein An organic substance that can collect on contact lenses, resulting in discomfort and cloudy vision.
-PRK (Photorefractive Keratectomy) Surgical procedure in which an excimer laser is used to remove corneal tissue to correct vision problems.
-Pupil The round, dark center of the eye, which opens and closes to regulate the amount of light the retina receives.
-Refractive surgery Surgery that corrects visual acuity, with the objective of reducing or eliminating the need for glasses and contacts.
Includes radial keratotomy, PRK, LASIK, and corneal implants.
-Replacement schedule How often you discard and replace your contact lenses: every day, week or two weeks (disposable); or every month, two months or calendar quarter (frequent replacement). It's important to differentiate between replacement schedule and wear schedule. Wear schedule is either daily wear (removed before sleeping) or extended wear (you may sleep with them in).
-Retina The sensory membrane that lines the eye; it is composed of several layers and functions as the immediate instrument of vision by receiving images formed by the lens and converting them into signals which reach the brain by way of the optic nerve.
-Retinal detachment Condition where the retina separates from the choroid.
-Retinitis pigmentosa Condition characterized by the progressive loss of peripheral vision, usually beginning with night blindness.
-RGP (Rigid Gas Permeable) Type of contact lens made of breathable plastic that is custom-fit to the shape of the cornea. RGPs are the successor to old-fashioned hard lenses, which are now virtually obsolete.
-Rod A photosensitive receptor in the retina that helps you to see in low light.
-RK (Radial Keratotomy) Surgical procedure where cuts are made in the cornea in a radial pattern, to flatten the cornea and correct myopia.
-Sclera The outer coat of the eyeball that forms the visible white of the eye and surrounds the optic nerve at the back of the eyeball.
segment A part, as in the near-vision portion of a pair of bifocals.
-Soft contact lenses Contacts made of gel-like plastic containing varying amounts of water.
-Solution Products used to clean, disinfect and store contact lenses.
-SPF (sun protection factor) Number representing the amount of sun something blocks. For example, if you normally begin to burn
after half an hour in the sun, a sunscreen with an SPF of 2 should let you stay out twice as long (1 hour), SPF 4 should let you stay out four times as long, and so on.
-Spherical A contact lens design that is like a sphere and is fairly common; in contrast, toric lenses for astigmatism are football-shaped and are less common.
-Spots Small, cloudy specks in the eye that become noticeable when they fall in the line of sight.
-Spring hinge Type of hinge on eyeglass frames that is more flexible than a regular hinge, making the frames more durable.
-Strabismus A misalignment of the eyes: they don't point at the same object together. Crossed eyes are one type of strabismus.
-Stroma The cornea's middle layer; it consists of lamellae (collagen) and cells, and makes up most of the cornea.
-Stye A blocked gland at the edge of the lid which has become infected by bacteria.
-Suspensory ligament Part of the eye that holds the lens in place.
-Temple The "arm" of a pair of glasses, running from the ear to the lens area.
titanium A type of metal alloy that is very strong. Eyeglasses made of titanium are lightweight and durable and often hypo-allergenic.
-Toric A lens design with two different optical powers at right angles to each other for the correction of astigmatism.
-Trifocal A lens design that has three focal areas: a lens for close work or reading, a lens for mid-distance viewing or arm's length, and a lens for faraway viewing or driving.
-Ultraviolet (UV) The invisible part of the light spectrum whose rays have wavelengths shorter than the violet end of the visible spectrum and longer than X rays. UVA and UVB light are harmful to your eyes and skin.
-Vitreous body Part of the eye between the lens and the retina, containing a clear jelly called the vitreous humor.
-Wear schedule How long you wear your contact lenses: either daily wear (you remove the lenses each night) or extended wear (you may sleep with them in). It's important to differentiate between wear schedule and replacement schedule -- that is, how often you discard and replace your lenses |
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