New - IOL Cataract Surgery

Eye care dictionary

ABLATION: The process of removing tissue by applying energy pulses from the excimer laser onto the surface of the cornea, thus reshaping the focusing surface of the eye.

ACCOMMODATION: The function of the eye's ability to focus on a wide range of distances. The lens and ciliary body in the eye change shape allowing the viewed object to be projected onto the retina.

ALGORYTHM: Formula used by the computer manufacturers to control the pattern delivered by the laser to reshape the cornea.

ASTIGMATIC KERATOTOMY: A procedure used to reduce astigmatism by placing small incisions, by hand, in the cornea.

ASTIGMATISM: A condition in which the cornea is "out of round". The surface is not spherical like the surface of a standard ball but more angular like the surface of a football.

BCVA (Best Corrected Visual Acuity): Usually refers to the best a person can see on the standard eye chart with their most accurate refraction in glasses or the phoropter testing equipment.

CATARACT: A cataract forms when the crystalline lens of the eye thickens, hardens, clouds, and loses ability to change shape. Normally, the onset of a cataract in one or in both eyes may cause decreased distance vision, night vision glare, impaired depth perception, and decreased color perception.

CILIARY MUSCLE: This muscle controls the accommodation of the lens. When the muscle relaxes, the lens adjusts for distance vision. When it contracts, the lens moves and changes shape for near vision.

CORNEA: The transparent front of the eye through which light enters. It is similar to the crystal on the front of a watch.

CORNEAL ABRASION: When the cornea is scratched by contact lenses, fingernails, tree branches, etc., it causes a small surface defect that heals spontaneously over the next few hours or days.

CORNEAL FLAP: A layer of tissue created by a microkeratome, under which the laser treatment is placed in the LASIK procedure.

CRYSTALLINE LENS: The lens of eye is located behind the iris and helps focus light on the retina.

EMMETROPIA: The term applied to the vision status of an individual when the eye is properly shaped and has "perfect" distance vision without correction.

ENHANCEMENT: A term used to describe a re-operation or re-treatment in refractive surgery. Primarily used in association with incisional surgeries, such as radial keratotomy and astigmatic keratotomy, it is used when there is still correction needed after the initial operation.

EPITHELIAL EROSION: Temporary loss of surface corneal cells, usually related to dryness or trauma.

EXCIMER LASER: An ultraviolet-based laser that generates energy pulses that when directed by computer control is used to reshape the surface of the cornea. It was originally designed for etching computer chips. It was approved by the FDA for use in the correction of nearsightedness in 1995.

FLUCTUATING VISION: A transient condition following most refractive surgery in which the patient’s vision may vary a bit, day to day, until stabilization. In LASIK this is usually about two weeks.

FOREIGN BODY SENSATION: A scratchy feeling that occurs whenever the corneal surface is temporarily disturbed, as in injuries or surgical procedures.

GLAUCOMA: Glaucoma is a condition in which the pressure inside the eye is too high for the eye to maintain its normal health.

HAZE: A type of healing reaction that causes cloudiness in the cornea following PRK. It is related to the loss of Bowman’s Layer in the PRK procedure.

HYPEROPIA (Farsightedness): Refractive error related to either a flat cornea or short eye length. The optical effect is that distant objects tend to be clearer than near objects.

INTRACORNEAL RINGS: Approved by the FDA in April 1999, these small acrylic arc-shaped implants are fed into tunnels created in the cornea, affecting a shape change in the cornea. Currently, they are used for mild degrees of nearsightedness only. In case of complication, they are theoretically reversible.

INTRAOCULAR LENSES (IOL's): Small lenses made of silicone, plastic, or acrylic material that are placed inside the eye following cataract removal. Some newer forms of these lenses are under FDA investigation for use in highly nearsighted and highly farsighted patients.

LASER IN-SITU KERATOMILEUSIS (LASIK): A surgical procedure in which a laser or microkeratome is used to create a surface layer of corneal tissue (flap) that can be reflected out of the way so that a laser re-surfacing treatment may be applied underneath. The flap is returned to its original position and heals very quickly.

MICROKERATOME: A surgical instrument used to cut the corneal flap in the LASIK procedure. There are several manufacturers and different methods by which they work.

MONOVISION: The process of treating one eye (mono) for distance and leaving one eye somewhat nearsighted for reading. This allows the greatest freedom from glasses use but also has the negative of reduced depth perception and the reduction of acuity that comes from two eyes adding image information together.

MYOPIA (Nearsightedness): Refractive error related to either a steep, or pointed cornea, or an eye of greater than usual length. The optical effect is that near objects are clearer than distance ones.

NIGHT VISION PROBLEMS: Many individuals complain of poor vision in the dark. This is essentially normal since the human eye is not designed for high night acuity. However, some of us have worse night vision than others. Unusual enlargement of the pupil in the dark, in some people, may contribute to this problem.

NOMOGRAMS: Tables created by surgeons to adjust the laser for individual patient treatments. Based on the major variables of age and amount of correction required.

OVERCORRECTIONS: The term applied to the situation when a refractive surgery treatment produces a change that is larger than that planned. This can happen in treatments for nearsightedness, farsightedness or astigmatism. Overcorrections are related to unusual healing responses, errors in pre-operative measurements, or nomogram use. Overcorrections can usually be remedied by the application of another, reversing type treatment.

PHOTOREFRACTIVE KERATECTOMY (PRK): Surgical procedure using the excimer laser to reshape the front surface of the eye, the cornea, to correct refractive errors. In this procedure, the laser pulses are applied directly through the surface of the cornea.

PRESBYOPIA: This is the condition, faced by all of us as we age, that causes us to require reading glasses for near focus. This is due to the progressive weakening of our focusing muscles, which begins in our youth and culminates in reading glasses, typically in our forties.

RADIAL KERATOTOMY (RK): Surgical procedure used to correct mild degrees of nearsightedness and astigmatism. This procedure involves making a series of small incisions in the cornea with a diamond knife to cause the cornea to change shape.

REGRESSION: This is the term applied to the situation when, following surgery for a refractive error, there is a tendency for the eye to shift somewhat back towards it original condition during the healing process. It is usually a relatively minor shift and can be adjusted with a re-treatment or enhancement procedure.

RETINA: The lining of the back of the eye upon which the images focused by the front of the eye fall. It is very specialized and serves as a living film to process the light impulses into the images that we "see".

RE-TREATMENT: A term equivalent to ENHANCEMENT but usually reserved for secondary treatments in laser corrections.

TOPOGRAPHY: A digital image processing device used to measure the shape of the cornea. It is used before refractive surgeries to identify certain individuals with conditions making refractive surgery an unacceptably unpredictable undertaking. It can also be used after surgery to identify unusual cornea shapes during the healing process.

UNDERCORRECTION: The term applied to the situation when a refractive surgery treatment produces a change that is less than that planned. This can happen in treatments for nearsightedness, farsightedness or astigmatism. Undercorrections are related to unusual healing responses, errors in pre-operative measurements, or nomogram use. Undercorrections can usually be remedied by the re-treatment process.