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| Aberration: An irregularity or departure from the norm. In this context, an imperfection in the eye affecting vision. | ||
| Ablation: Varying slightly from sphericity and having less aberration. | ||
| Aspheric/Asphericity: Surgical removal of tissue using an excimer laser. | ||
| Astigmatism: A vision problem that results in blurred distance and/or near vision. Light rays entering the eye are bent unequally, which prevents the formation of a sharp point of focus on the retina. This creates a blurring of parts of objects you see. | ||
| Broad-beam: A laser with a relatively large (6-8mm) diameter beam that can be manipulated to reshape the cornea in a refractive surgery procedure. | ||
| Buttonhole Flap: Complication for the LASIK procedure where the surgeon intends to make a flap of equal thickness throughout, but ends up with a flap where the center of the flap is very thin. | ||
| Cataract: Clouding of the lens inside the eye that can lead to a loss of vision. | ||
| CK: An acronym for Conductive Keratoplasty, a refractive surgical procedure which uses radio frequency (RF) energy to heat and shrink the corneal tissue. This "steepens" the cornea to create the desired refractive effect. | ||
| Collagen: The principal protein of the skin, tendons, cartilage, bone and connective tissue. | ||
| Coma: A higher order aberration which makes items appear to have a comet-shaped "tail", creating blurring in your vision. | ||
| Cornea: The clear front surface of the eye. Refractive surgeries like PRK, LASIK and RK reshape this surface to correct vision problems. | ||
| Corneal flap: A thin slice of tissue on the surface of the cornea made with a microkeratome at the beginning of a LASIK procedure. This flap is folded back before the laser is applied to the inner layers of the cornea. | ||
| Diopter: A unit of measurement for myopia, hyperopia and astigmatism that usually falls within a scale of +14 to -14. A positive number indicates hyperopia and a negative number indicates myopia. Positive and negative numbers are also used to indicate astigmatism. Whether the number is positive or negative, the higher the number the greater the extent of the vision problem. | ||
| Dry eye: Dryness of eye tissue due to deficient tear production that can cause burning, stinging and the feeling that something is in the eye. This occurs commonly in post-LASIK patients in the weeks following surgery. | ||
| Enhancements: A follow-up procedure or retreatment. LASIK is sometimes performed a second time if the results were not satisfactory after the first procedure. Speak with your doctor to understand this process more fully. | ||
| Epithelium: The protective layer of cells covering the cornea. | ||
| Excimer laser: A type of laser used in laser vision correction that removes tissue from the cornea. | ||
| Farsightedness: A common term for hyperopia, a vision problem that most commonly results in blurred close vision. Moderate to severe hyperopia may also result in blurred distance vision. The cornea and lens focus light rays behind, rather than directly on, the retina. | ||
| FDA: An acronym for the Food and Drug Administration, a federal agency within the U.S. Department of Health and Human Services responsible for determining the validity and safety of any drug, cosmetic, or medical device. | ||
| Femtosecond Laser: A laser which emits optical pulses with a duration of very small and very rapid, billionths-of-a-second laser "bursts" to create a corneal flap | ||
| Free cap: Complication from the LASIK procedure, where the surgeon intends to make a hinged flap of tissue, but ends up without a hinge. This type of flap is called a free cap. | ||
| Gaussian beam: A type of small-spot laser beam, its unique rounded shape leaves the corneal surface smooth. | ||
| Glaucoma: A condition usually associated with high eye pressure. This condition results in damage to the nerve at the back of the eye and possible loss of vision. | ||
| Globe Penetration: Complication from the LASIK procedure where the surgeon intends to make a corneal flap, but ends up going through the entire cornea, penetrating into the eye. | ||
| Halo: A circular flare or hazy ring that may appear around a headlight or other lighted object. This symptom may occur after surgery. | ||
| Halos: A visual effect, in which a circular flare or hazy ring of light may appear around a headlight or other lighted object. | ||
| Higher order aberrations: A collective term for a series of imperfections in the eye's optical system that may result in vision problems experts believe to be responsible for low-light vision difficulties. | ||
| Hyperopia: A vision problem that most commonly results in blurred close vision although moderate to severe hyperopia may also result in blurred distance vision. The cornea and lens focus light rays behind, rather than directly on, the retina. | ||
| Intraocular Lenses (IOLs): Artificial lenses made of plastic, silicone, or acrylic which are implanted in the eye to improve its focus and correct vision problems. | ||
| LASEK: An acronym for Laser Assisted sub-Epithelial Keratectomy, a refractive surgical procedure which uses an instrument called a trephine to remove the surface cells (epithelium) of the cornea prior to laser treatment. Once the laser ablation is completed, the surface cells are replaced over the reshaped area. | ||
| LASIK: An acronym for Laser In-Situ Keratomileusis. LASIK is a type of laser surgery in which the cornea is reshaped to improve vision. A device called a microkeratome is used to surgically create a thin, hinged flap of corneal tissue. The flap is folded back, the laser is directed to the corneal surface exposed beneath the flap and the flap is brought back into place. | ||
| Lens: A structure inside the eye that helps to focus light on to the back of the eye. | ||
| Lower order aberrations: A collective term for a series of common vision problems including myopia, hyperopia and astigmatism. | ||
| Microkeratome: A surgical instrument used to cut a flap of corneal tissue as the first step in the LASIK procedure. | ||
| Mixed astigmatism: A type of astigmatism that results in blurred distance and near vision. Light rays entering the eye are bent at different points, with one point focused in front of the retina and the other point focused behind the retina. Clear vision requires that all focus points be directly on the retina. | ||
| Monovision: An approach to LASIK that intentionally corrects one eye for distance vision and the other for close vision. | ||
| Myopia: Another term for nearsightedness. A condition of the eye that results in blurred distance vision. The cornea and lens focus light rays from distant objects in front of the retina. This incorrect focusing of light results in blurred images of objects at a distance. | ||
| Nearsightedness: A common term for myopia. A condition of the eye that results in blurred distance vision. The cornea and lens focus light rays from distant objects in front of the retina. This incorrect focusing of light results in blurred images of objects at a distance. | ||
| Ocular: Having to do with the eye. | ||
| Ophthalmologist: A medical doctor who specializes in the eye and is licensed to perform surgery on the eye. All LASIK surgeons are ophthalmologists. | ||
| Ophthalmology: The art and science of eye medicine. | ||
| Optometrist: An eye care specialist who specializes in the examination, diagnosis, treatment, management and prevention of diseases and disorders of the eye and associated structures. | ||
| Photorefractive Keratectomy: Commonly referred to as PRK, it is a common laser vision correction procedure. PRK uses an excimer laser to remove tissue directly from the surface of the cornea. | ||
| Presbyopia: A condition commonly due to aging, is due to a stiffening of the lenses, which results in an eye that can no longer accommodate for near or "reading" vision. The individual is no longer able to read clearly and requires reading glasses. | ||
| PRK: An acronym for Photorefractive Keratectomy, a refractive surgery procedure that uses an excimer laser to remove tissue directly from the surface of the cornea. | ||
| Refractive errors: Vision problems caused by an imperfect optical system, most commonly myopia, hyperopia and astigmatism. | ||
| Refractive surgery: Any surgical procedure performed to change the eye`s refractive error. | ||
| Retina: The light sensitive nerve layer in the back of the eye that receives visual stimuli that are transmitted to the brain. | ||
| Saccadic movements: Involuntary eye movements. These rapid eye movements occur all the time, including during laser refractive surgery and may affect accurate placement of the laser beam. | ||
| Spherical aberration: A visual disorder reflecting a change in curvature between the center and edge of the pupil. This creates multiple focal points and can cause halos in your vision. | ||
| Tracking device: A component of some (but not all) laser vision correction systems designed to monitor the movement of the eye during the procedure. | ||
| Visual acuity: Another phrase for visual clarity, a measure of the eye's ability to distinguish the shape of objects. Visual acuity is measured with a traditional eye chart, with the goal traditionally being 20/20. | ||
| Wavefront device: A sophisticated measurement device, which passes a narrow ray of eye-safe light through the optical system and measures the optical distortions as the light exits the eye. With the ZYWAVE® system, the resulting wavefront maps are used to provide fully customized vision correction, to address both lower and higher order aberrations, through the ZYOPTIX® procedure. | ||
| ZYOPTIX®: The branded name for the world's first customized laser vision correction procedure that addresses both higher and lower order aberrations to create truly customized vision correction. | ||
| Wavefront maps: A sophisticated way to represent visual disorders, these 3-dimensional maps are created by passing a narrow ray of light through the optical system and measuring the optical distortions as the light exits the eye. | ||
| Aberrometer: A sophisticated measurement device, which measures the eye's lower order and higher order abberations. | ||
| Subtractive effect: When two or more higher order abberations interact with each other making the image clear. | ||
| Additive effect: When two or more higher order abberations interact with each other making the image blurry. | ||
| Quantitative: Establishes where your vision is on a 20/20 numeric scale. | ||
| Qualitative: Establishes where your vision is placed on a three-dimensional wavefront map. | ||
| Snellen chart: A device used to measure your quantity of vision by establishing where your vision is on a 20/20 numeric scale. | ||
| Glare: A visual effect occurring in low light levels, in which an oppressive or brilliant light may appear around lighted objects. This symptom may occur after surgery. | ||
| Spherical: A higher order aberration which makes it hard to see "edges" of items in low light conditions. Some people refer to this as glare. | ||
| Trefoil: A higher order aberration which makes items appear to have "starbursts" around them in low light conditions. | ||
| Quantitative Measurement of Your Vision: Measuring quantitative factors means diagnosing and measuring lower order aberrations using traditional vision testing devices called a phoropter and snellen chart. These devices create numerical numbers by establishing where your vision is placed on a numeric chart. If your visual acuity is determined to be 20/20, you will see at 20 feet what a person with normal vision sees at 20 feet. If you have 20/40 vision, you will see at 20 feet what a person with 20/20 vision sees at 40 feet. | ||
| Qualitative Measurement of Your Vision: Measuring qualitative factors means diagnosing and measuring higher order aberrations using a wavefront-scanning device called an aberrometer. The aberrometer creates a 3 dimensional map by passing a narrow ray of light through a patient’s entire optical system and measuring the smallest refractive errors as the light exits the eye. Is 10X more accurate than traditional testing devices. | ||
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