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LASIK Glossary
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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.

Aberrometer
A 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 zone
The area of tissue removed during LASIK surgery.

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

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

Acuity
Sharpness, or clearness of vision.

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

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

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

Bausch & Lomb
Manufacturer 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.

Cornea
The 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.

Diopter
The measurement unit of refractive error. A negative diopter value signifies an eye with myopia and 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 in one meter.

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

Dry Eye Syndrome
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.

Endothelium
The inner layer of cells on the inside surface of the cornea.

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

Epithelium
The outermost layer of cells of the cornea and the eye's first defense against infection.

Excimer laser
An 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.

Farsightedness
The 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.

Glare
The 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.

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

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

High Definition LASIK
Otherwise described as wavefront guided, or custom LASIK.

Higher order aberrations
Refractive errors that cannot be corrected with glasses or contacts, other than nearsightedness, farsightedness, and astigmatism.

Hyperopia
The inability to see distance 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. May be a causative factor of pre-mature presbyopia (difficulty with near reading), occurring before the age of 40.

Intralase
Flap 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.

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

Keratectomy
The surgical removal of corneal tissue.

Keratotomy
A surgical incision (cut) of the cornea.

Keratitis
Inflammation of the cornea.

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

Keratomileusis
Carving of the cornea to reshape it.

LASIK
The 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.

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

Microkeratome
A 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 C
An intra-operative medication applied to the surface of the cornea to prevent hazing of the cornea post-operatively.

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

Myopia
The 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.

Nearsightedness
The clinical term being myopia

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

Optometrist
An 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.

PRK
The acronym for Photorefractive Keratectomy which is a procedure involving the removal of the surface layer of the cornea (epithelium) and 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.

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

Pupil
A 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 Keratotomy
Radial 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.

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

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

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

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

Retina
A 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.

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

Stroma
The middle, thickest layer of tissue in the cornea.

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

Wavefront
A 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.

Zyoptix
A 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.

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