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LASIK Glossary

If you are interested in learning more about the technology and science behind LASIK eye surgery we have provided a LASIK Glossary to help you better understand some of the terms associated with this eye surgery.

AberrometerA diagnostic device developed by Bausch & Lomb to quantify higher-order optical aberrations corrected by their Zyoptix excimer laser system. The patient’s eye is scanned by the aberrometer to produce the data disk which is used in the Zyoptix wavefront treatment. This data is uniquely derived for your eye only.

Ablation zoneThe area of tissue removed during LASIK surgery.

AccommodationThe ability of the eye to change its focus from distant objects to near objects.

AcuFocus 7000 ACI corneal inlayA type of lens placed under the LASIK flap designed to allow one to see at both near and distance. Currently under FDA investigation.

AcuitySharpness, or clearness of vision.

Advanced Surface AblationRemodeling of the corneal surface with wavefront-guided correction. Usually performed under a thin Epi-LASIK flap. The best results are with the application of topical Mitomycin C drops at the time of surgery.

AlconA major eye care product manufacturer that also makes an excimer laser for LASIK eye surgery.

AstigmatismPhysical irregularities in the cornea or lens causing distortion of the image on the retina.

Bausch & LombManufacturer of the Technolas 217 excimer laser with Zyoptix, which in the opinion of Dr. Ellis is currently the best available excimer laser on the market.

CorneaThe cornea is the first part of the eye that bends (or refracts) the light and provides most of the focusing power. It is the front part of the eye.

DiopterThe measurement unit of refractive error. A negative diopter value signifies an eye with myopia and a positive diopter value signifies an eye with hyperopia. A lens with one diopter of refractive power will bend parallel rays of light to a point focus on one meter.

DLK – Diffuse Lamellar KeratitisAn inflammatory condition which may occur post-LASIK and is treated with topical corticosteroid drops and/or irrigation beneath the LASIK flap.

Dry Eye SyndromeIt is a common, but often treatable condition. The eyes do not produce enough tears to keep them moist and comfortable. Symptoms of dry eye include pain, stinging, burning, scratchiness, and intermittent blurring of vision. It is usually treated with artificial tear drops, punctum plugs, cyclosporin ophthalmic drops (RESTASIS), and flaxseed tablets.

EndotheliumThe inner layer of cells on the inside surface of the cornea.

Epi-LASIKA modification of advanced surface ablation performed under an ultra-thin 30-micron epithelial flap created by a special device called an epithelial separator.

EpitheliumThe outermost layer of cells of the cornea and the eye’s first defense against infection.

Excimer laserAn ultraviolet laser used in refractive surgery to remove corneal tissue. This is the laser used for LASIK, manufacturers include VISX, Bausch & Lomb, Alcon, Nidek, and Allegretto.

FarsightednessThe clinical term being hyperopia. This occurs when light entering the eye focuses behind the retina, instead of directly on it. A flatter cornea or an eye that is shorter than a normal eye causes this.

GlareThe scattering of bright light caused by imperfections in the optical system which is often a cause of decreased vision. This might be a side effect of LASIK treatment with older excimer lasers. Most often caused by higher-order optical aberrations which can often be substantially reduced by wavefront-guided LASIK.

HalosOptical imperfections in or in front of the eye that cause rings around lights. This may be substantially reduced by wavefront-guided LASIK.

HazeThe sensation of looking through smoke or fog caused by corneal clouding.

High Definition LASIKOtherwise described as wavefront-guided, or custom LASIK.

Higher-order aberrationsRefractive errors cannot be corrected with glasses or contacts, other than nearsightedness, farsightedness, and astigmatism.

HyperopiaThe inability to see distant objects clearly without lenticular accommodation. Also known as farsightedness. Individuals with hyperopia have difficulty reading as well because additional accommodation is required to bring near objects into focus in addition to the accommodation required for distance. Maybe a causative factor of pre-mature presbyopia (difficulty with near reading), occurring before the age of 40.

IntralaseFlap creation with a femtosecond laser instead of a microkeratome. The laser creates postage-stamp-like perforations which must be torn or lysed to create the LASIK flap. Dr. Ellis feels that the smoothest flaps are created with the microkeratome which he prefers to Intralase.

IrisThe colored tissue immediately in front of the lens whose center is the pupil of the eye.

KeratectomyThe surgical removal of corneal tissue.

KeratotomyA surgical incision (cut) of the cornea.

KeratitisInflammation of the cornea.

KeratoconusA disorder characterized by an irregular corneal surface (cone-shaped) resulting in blurred and distorted images.

KeratomileusisCarving of the cornea to reshape it.

LASIKThe acronym for laser-assisted in situ keratomileusis which refers to creating a flap in the cornea with a microkeratome and using a laser to reshape the underlying cornea.

LensA part of the eye that provides some focusing power. The lens is able to change shape allowing the eye to focus at different distances.

MicrokeratomeA surgical device that is affixed to the eye by use of a vacuum ring. When secured, a very sharp blade cuts a layer of the cornea at a predetermined depth.

Mitomycin CAn intra-operative medication applied to the surface of the cornea to prevent hazing of the cornea post-operatively.

MonovisionThe purposeful adjustment of one eye for near vision and the other eye for distance vision.

MyopiaThe inability to see distant objects as clearly as near objects. Nearsightedness or myopia occurs when light entering the eye focuses in front of the retina instead of directly on it.

NearsightednessThe clinical term being myopia

OphthalmologistA medical eye doctor capable of performing eye surgeries. All ophthalmologists are physicians with an MD degree who undergo further training in eye surgery.

OptometristAn eye care provider, who diagnoses eye problems, fits contact lenses, and prescribes glasses. Optometrists often work together with an ophthalmologist when creating a treatment plan for a patient. Optometrists do not have an MD degree but have studied at a school of optometry.

PRKThe acronym for Photorefractive Keratectomy which is a procedure involving the removal of the surface layer of the cornea (epithelium) and the use of a computer-controlled excimer laser to reshape the stroma. Best results for PRK are achieved when performed by Advanced Surface Ablation to reshape the corneal stroma.

PresbyopiaThe inability to maintain a clear image (focus) as objects are moved closer. Presbyopia is due to a reduced ability of the crystalline lens to change shape with increasing age.

PupilA hole in the center of the iris that changes size in response to changes in lighting. It gets larger in dim lighting conditions and gets smaller in brighter lighting conditions.

Radial KeratotomyRadial keratotomy involves the precise placement of microscopic incisions in the cornea to change its curvature. The object of the procedure is to flatten the cornea and thus correct the nearsightedness by allowing rays of light to focus properly on the retina.

RefractionA test to determine the refractive power of the eye; also, the bending of light as it passes from one medium into another.

Refractive ErrorsImperfections in the focusing power of the eye, for example, hyperopia, myopia, and astigmatism.

Refractive PowerThe ability of an object, such as the eye, to bend light as light passes through it.

RestasisAn ophthalmic medication consisting of cyclosporin drops used to increase tear production in patients suffering from dry eye.

RetinaA layer of fine sensory tissue that lines the inside wall of the eye. The retina acts like the film in a camera to capture images, transforms the images into electrical signals, and sends the signals to the brain.

ScleraThe tough, white, outer layer (coat) of the eyeball that, along with the cornea, protects the eyeball.

StromaThe middle, thickest layer of tissue in the cornea.

VISXA popular manufacturer of laser vision correction excimer lasers recently acquired American Medical Optics (AMO).

WavefrontA measure of the total refractive errors of the eye, including nearsightedness, farsightedness, astigmatism, and other refractive errors called higher-order aberrations that cannot be corrected with glasses or contacts.

ZyoptixA modification to the Bausch and Lomb Technolas 217 excimer laser which corrects high order optical aberrations not normally treated with standard excimer lasers. Derived from NASA space telescope technology this system helps to eliminate the side effects of glare and halo which may occur with other excimer laser systems.

Otherwise referred to as wavefront custom correction, the Zyoptix system has the potential to improve visual acuity beyond 20/20.