A

Ablate, ablation
To remove tissue during surgery, often with a laser.

Accommodation
The ability of the eye's natural lens to change shape so it can focus on objects at various distances.

Accommodative lens
A type of intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems). Has a fixed focal point but physically changes shape inside the eye in response to eye muscle movements to adjust for clear vision at near, intermediate or far distances.

Age-related macular degeneration (AMD)
Leading cause of vision loss and legal blindness in adults over age 60. Affects the sharp, central vision necessary for reading, driving and other daily activities. Impacts the macula (the centermost part of the retina, responsible for seeing fine detail). Occurs in two forms - dry AMD and wet AMD. Wet AMD is more serious.

Alpha-blockers
Muscle-relaxing medications that treat prostate enlargement and other conditions.

Anesthetic
Medicine that causes a loss of sensation including loss of pain. Local anesthetic causes numbness and pain relief in a localized area, such as the eye, without affecting the senses in the rest of the body.

Astigmatism
Common vision problem and type of refractive error. Caused by either irregularity in the curvature of the cornea or the lens of the eye. People with astigmatism generally have difficulty seeing fine details at all distances. Treated with corrective lenses, laser vision correction or toric IOLs.

Autoimmune diseases
Medical conditions characterized by exaggerated immune responses. These exaggerated responses occur against substances and tissues normally present in the body, meaning that the body attacks its own cells. These reactions may be restricted to certain organs or they may involve a particular kind of tissue throughout the body. Examples of autoimmune diseases include multiple sclerosis, Crohn's disease, psoriasis, rheumatoid arthritis, Sjögren's syndrome and others. Treatment typically involves medication to decrease immune response.

B

Benchmarking
Comparing processes and performance metrics to standard or best practices. Measures relative effectiveness. For eye surgeons, performance metrics may include costs, cycle time, productivity and quality of patient outcomes. Helps physicians, patients and third parties understand where a medical practice or procedure is in relation to a particular standard and to plan improvements.

Bifocals
Eye glasses that combine two lenses made for focusing at different distances. Typically the upper lens provides clear distance vision and the lower lens clear close vision for reading and seeing fine details.

Blepharitis
Inflammation of the eyelids with crusting of the eyelashes. May increase risk of infection or inflammation of the cornea after LASIK.

C

Cafeteria plans
Service offerings from a doctor's office that enable patients to select a number of services from a list. For example, the basic fee might include only an initial procedure and the cafeteria plan would allow patients to select additional follow-up visits, enhancements or touch-up procedures as part of their entire service package.

Capsular bag or lens capsule
Thin membrane that holds the eye's lens. Located behind the iris (the colored part of the eye). Part of the capsular bag is retained after cataract surgery and the intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems) is placed within it.

Cataract
Clouding of the eye's lens that blocks passage of light to the retina, resulting in impaired vision. Often a result of normal aging, cataracts form when protein clumps cloud areas of the eye's lens. As the cataract progresses, vision worsens and often requires surgical replacement of the damaged lens with an artificial one.

Choroid
Underlying layer of blood vessels in the eye that nourish the retina.

Conventional LASIK
Laser surgery that corrects the main types of refractive error (nearsightedness, farsightedness and astigmatism) based on your prescription for glasses or contacts. Conventional LASIK is usually compared to Wavefront-guided and Wavefront-optimized LASIK, variations of LASIK surgery that are more customized to each individual's eyes.

Cornea
Clear, curved surface at the front of the eye through which light enters the eye. Along with the sclera (the white part of the eye), provides external protection for the eye. Often called the window of the eye. During many types of vision correction surgery, such as LASIK, the cornea is reshaped to reduce or eliminate the main types of refractive error - nearsightedness, farsightedness and astigmatism.

Corneal flap
Thin slice of tissue on the surface of the cornea made at the beginning of LASIK surgery. Made with either a microkeratome or a femtosecond laser. The flap is folded back before the LASIK procedure can shape the inner layers of the cornea.

Corticosteroids
Class of steroid hormones used to treat a variety of inflammatory conditions. Chronic use may lead to formation of posterior subcapsular cataracts.

D

Diabetes
Disease in which the body does not produce enough, or properly use, the hormone insulin. Most Americans who are diagnosed with diabetes have type 2 diabetes. Can often lead to vision problems such as diabetic retinopathy.

Diabetic retinopathy (DR)
Complication of diabetes that compromises vision and can lead to blindness. Tiny blood vessels in the retina are weakened and leak blood and fluid into the eye, which can progress to new abnormal blood vessel growth on the retinal surface, further affecting vision. Between 40 and 45 percent of American adults with diabetes have some form of diabetic retinopathy.

Dilated
Made wider or larger. In eye health, usually refers to the pupil (the hole in the center of the iris that opens and narrows in response to light levels). During an eye examination and certain types of eye surgery, drops will be used to dilate or open the pupil.

Diopters
A measurement of refractive error. Hyperopia (or farsightedness) is measured in terms of positive diopters (+1, +2). Myopia (or nearsightedness) is measured in terms of negative diopters (-1, -2). Most refractive errors fall somewhere between +6 to -6 diopters.

Distance vision
Vision that allows you to see objects far away.

Dry eye
A syndrome characterized by corneal dryness due to deficient tear production. Often related to hormonal changes, local atmospheric conditions and many other causes. Approximately 42 million Americans experience this condition.

E

Ectasia
Progressive thinning and bulging of the cornea (the clear outer covering of the eye).

Epithelial defects
Defects in the epithelium (protective layer of cells on the cornea) can allow invasion by bacteria, fungi, viruses or Acanthamoeba. Can be initiated by mechanical trauma or nutritional deficiencies. Symptoms are progressive redness, foreign body sensation, ache, sensitivity to light and tearing.

Epithelial ingrowth
A complication of LASIK in which epithelial cells (cellular tissue that covers the outside of body surfaces, including the outside of the cornea) grow underneath the corneal flap.

Epithelium or epithelial layer
Cellular tissue that covers the outside of body surfaces, including the outside of the cornea (the clear outer covering of the eye).

Extracapsular surgery
Older surgical technique typically reserved for very dense or hard cataracts and other special circumstances. Involves a larger incision, about three-eighths of an inch, so that the hard central portion of the eye's natural lens can be removed in one piece.

Excimer laser
Type of "cold" laser that emits ultraviolet light. Used in refractive surgery to remove corneal tissue and reshape the corneal surface.

F

Farsighted, farsightedness (or hyperopia)
Common vision problem and type of refractive error. Caused by too little curvature of the cornea or too little distance between the front of the eye and the retina at the back. Both structural defects cause light entering the eye to focus incorrectly on the retina, resulting in blurred close-up vision. Treated with corrective lenses, laser vision correction or multifocal or accommodative IOLs.

Femtosecond Laser
Type of high energy laser used in "all-laser" or "bladeless" LASIK to create the corneal flap.

G

Glare
Appearance of additional luster around lights that can interfere with vision, especially night vision. Sometimes occurs as a side effect of LASIK surgery and often decreases with time. May also be caused by cataracts or other eye conditions.

Glaucoma
Eye disease characterized by too much pressure inside the eye (intraocular pressure). Can cause eye damage and vision loss. Symptoms may include halos around lights, tunnel vision and vision loss. Many patients have no symptoms until severe visual field loss has occurred. Treated with medications or sometimes eye surgery.

H

Halos
Appearance of rings around lights at night. Sometimes occur as a side effect of LASIK surgery and often decreases with time. May also be caused by cataracts or other eye conditions.

Haptics
Specialized arms designed to secure the intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems) after placement within the eye's capsular bag.

Higher order aberrations
More complex irregularities of the eye that can cause vision problems such as difficulty seeing at night, glare, halos, starbursts or double vision. Some small degree of higher order aberrations are normal and do not usually cause noticeable vision problems.

I

Intraocular pressure
Pressure within the eye cause by the tension between the fluid inside the eye and the eye itself.

Intraocular lens (IOL)
Artificial lens made of plastic, silicone or acrylic. Designed to be implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems, such as cataracts and presbyopia.

Intravenous fluids
Fluids (such as drugs, blood plasma, etc.) introduced directly into a vein by means of a hypodermic needle.

Iris
Colored membrane in front of the eye's lens that manipulates the size of the pupil and thus regulates the amount of light entering the eye.

K

Keratoconus
Degenerative eye disorder in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve. Can cause substantial distortion of vision, including multiple images, streaking and sensitivity to light. Typically diagnosed during adolescence and is most severe by the patient's 20s and 30s. If afflicting both eyes, deterioration in vision can affect the patient's ability to drive a car or read normal print.

Keratomileusis
Reshaping of the cornea which was done with a lathe and blade before the development of LASIK techniques.

L

Laser vision correction
A class of surgeries where a laser is used to reshape the cornea to correct refractive errors. LASIK, PRK, LASEK and Epi-LASIK are all types of laser vision correction.

LASIK Monovision
LASIK surgery to correct vision so that one eye focuses clearly on far objects and the other eye focuses clearly on near objects. The brain combines the two images to create clear vision at all distances.

LASIK (laser in-situ keratomileusis) surgery
Type of laser surgery in which the cornea is reshaped to improve vision. Either a microkeratome or a femtosecond laser is used to surgically create a thin, hinged flap of corneal tissue. The flap is folded back, and an excimer laser is directed to the corneal surface exposed beneath the flap to reshape the cornea for corrected vision. Then the flap is brought back into place.

Lens
The transparent disc behind the pupil that brings light into focus on the retina. As the eye ages, the lens often becomes cloudy and is called a cataract.

M

Microkeratome
Precision surgical instrument used to create the corneal flap in the uppermost layer of the cornea during LASIK.

Monofocal (or "standard") intraocular lens
Type of intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems) designed to provide clear vision at one fixed focal point (usually for clear distance vision).

Monovision
Vision correction that eliminates need for bifocals or reading glasses by correcting one eye for clear distance vision and the other for clear up-close vision. The brain combines the two images to create clear vision at all distances.

Multifocal intraocular lens
Type of intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems) designed to include corrections for near, intermediate and distance vision in the same lens.

N

Nearsighted, nearsightedness (or myopia)
Common vision problem and type of refractive error. Caused by either too much curvature of the cornea or too much distance between the front of the eye and the retina at the back. Both structural defects cause light entering the eye to focus incorrectly on the retina, resulting in blurred distance vision. Treated with corrective lenses, laser vision correction or multifocal or accommodative IOLs.

O

Ophthalmologist
Doctor of medicine (M.D.) or doctor of osteopathy (D.O.) who is qualified to diagnose, manage and treat all eye and visual system disorders. An ophthalmologist is trained to render total eye care, including vision services, contact lenses, eye examinations, medical eye care and surgical eye care.

Optometrist
Eye health professional trained to provide primary eye care services, such as basic eye health and vision examinations, diagnosis of vision problems and eye diseases and prescriptions for eyeglasses, contact lenses and medications.

Overcorrection
When the change to refractive error after refractive surgery exceeds the attempted correction.

P

Phacoemulsification
Also known as "small incision cataract surgery" or "phaco." Used in the majority of cataract surgeries performed today. Involves making a small incision on the side of the cornea and inserting a tiny probe that emits ultrasound waves to soften and break the lens of the eye into pieces, which are then suctioned out.

Presbyopia
Also called age-related focus dysfunction. Common vision problem that develops naturally over time. Characterized by loss of the eye's ability to focus at close distances or on fine details. Treated with reading glasses, contact lenses, presbyopia laser vision correction (also called LASIK monovision) or presbyopia lens replacement surgery.

Pupil
The black, circular area in the center of the iris (the colored part of the eye) that regulates the amount of light entering the eye by constricting and dilating.

R

Refractive error
Irregularities in the cornea, lens or shape of the eye that prevent correct focus at any distance.

Refractive surgery
Any surgical procedure that attempts to decrease the patient's refractive error (irregularities in the eye that prevent correct focus). LASIK surgery is a common type of refractive surgery as is lens replacement.

Regression
A backwards shift from the initial visual outcome after eye surgery to improve vision.

Retina
Transmitter at the back of the eye that contains blood vessels and nerves and sends images to your brain through the optic nerves.

Retinal detachment
Serious condition occurring when part of the retina lifts or pulls away from its natural position. may result in significant vision impairment or blindness in just a matter of days if left untreated.

S

Sclera
White part of the eye. Provides external protection for the eye, along with the cornea (the clear outer covering of the eye).

Starbursts
Appearance of rays or fine filaments of light coming off a light source, such as a headlight of a car. Can become longer and denser at night. Severity of starbursts varies-they may be experienced differently in terms of size, shape, length of rays, the density of rays and transparency (whether the light source is visible through the starburst). Sometimes occur as a side effect of LASIK surgery and often decreases with time. May also be caused by cataracts or other eye conditions

T

Tear film
A very thin film of water and other chemicals riding on top of the epithelium (protective layer of cells on the cornea) that lubricates the front of the eye.

Tear gland
Also called lacrimal glands. Paired almond-shaped glands, one for each eye, that secrete the aqueous layer of the tear film. They are situated in the upper, outer portion of each eye cavity.

Toric lens
Type of intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems) designed to correct moderate to severe astigmatism.

U

Ultrasound, ultrasonic energy
High frequency sound waves used during cataract surgery to break up the eye's natural lens so that it can be easily removed and replaced with an intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems).

Undercorrection
When the desired change to refractive error is not fully achieved after refractive surgery.

V

Vitreous fluid
Clear, colorless substance that fills the eyeball between the lens and the retina.

Vitreoretinal surgery
Surgery involving the vitreous humor and the retina. Includes treating retinal tears and detachments, diabetic retinopathy, macular degeneration, ocular trauma, ocular tumors, inflammatory ocular conditions, hereditary retinal diseases and a variety of less common, highly complex disorders.

W

Wavefront-guided LASIK
Also called custom LASIK. Creates a personalized map of existing higher order aberrations to correct refractive error and these more subtle vision problems. In some cases, existing higher order aberrations are severe enough to require this special treatment.

Wavefront-optimized LASIK
Newer LASIK technology that corrects refractive errors while accounting for both the natural curvature of the eye and the unique characteristics of each individual's eye. Has less risk of inducing higher order aberrations than conventional LASIK

Y

YAG laser capsulotomy, YAG laser treatment
Procedure sometimes necessary following cataract surgery or presbyopia lens replacement when clouding develops in the vision. Painless in-office procedure. Uses a Yttrium-Aluminum-Garnet (YAG) laser to create a small hole in the membrane behind the intraocular lens (artificial lens implanted in the eye in place of or in front of the natural lens to improve focus and correct vision problems) to allow light through and restore clear vision.

Z

Zonule
Ligaments in the eye that connect the capsular bag to the muscles in the ciliary body (part of the eye that includes the ciliary muscle and components that produce aqueous fluid).