Glossary

Ablate

In surgery, to remove

Removal of tissue with the excimer laser

Zone

Area of tissue that is removed during laser surgery

Acuity

Clearness or sharpness of vision

Astigmatism

A defect of vision in which the image of an object is distorted, usually due to a football-shaped curvature of the cornea.

Automated Lamellar Keratoplasty (ALK)

A refractive surgery procedure for patients with high nearsightedness where a “pancake” of corneal tissue is removed with a microkeratome.

Cornea

The transparent circular part of the front of the eyeball. It refracts the light entering the eye to focus it onto the retina.

Corneal Topography

A computer-generated map of the surface curvature of the cornea.

Corneal Transplantation

A diseased or scarred cornea is replaced with a healthy cornea.

Diopter

Tthe measurement of refractive error; a negative diopter signifies an eye with myopia (nearsightedness), a positive diopter signifies an eye with hyperopia (farsightedness)

Endothelium

Layer of cells on the inside surface of the cornea

Epithelium

Outermost layer of cells of the cornea and the eye’s first defense against infection

Glare

Complication of refractive surgery in which scatter from bright light decreases vision

Halo

Complication of refractive surgery in which patient sees rings around lights due to optical imperfections in or in front of the eye

Hyperopia

Farsightedness.

In Situ

A Latin term meaning “in place” or not removed

Iris

The colored part of the eye; suspended behind the cornea and immediately in front of the lens

Keratectomy

Surgical removal of corneal tissue

Keratotomy

Surgical incision of the cornea

Keratitis

Inflammation of the cornea

Kerato

Prefix indicating relationship to the cornea

Keratoconus

Rare, inherited disorder characterized by an irregular corneal surface (cone-shaped) resulting in blurred and distorted images

Keratomileusis

Surgical reshaping of the cornea

Keratoplasty

Replacement of the cornea

Laser Correction of Nearsightedness

Vision is corrected or improved with an excimer laser, which uses a very thin beam of light of high energy to sculpt small amounts of tissue from the corneal surface, also called photorefractive keratectomy (PRK) or LASIK.

LASIK

LASIK refers to Laser In Situ Keratomileusis. After a “pancake” of corneal tissue is prepared and folded back, the excimer laser is used to sculpt a small amount of corneal tissue to correct nearsightedness.

Lens

Part of the eye that changes shape, allowing the eye to focus at different distances

Microkeratome

Instrument a surgeon uses to create the corneal flap in the uppermost layer of the cornea during the LASIK procedure

Monovision

Purposeful adjustment of dominant eye for distance vision and the other for near vision

Myopia

Nearsightedness.

Nomogram

Surgeon’s adjustment to the laser’s computer calculation to further refine results

Overcorrection

Complication of refractive surgery where the desired amount of correction exceeds attempted results

Phototherapeutic Keratectomy (PTK)

An excimer laser treatment for patients with diseases of the cornea, corneal dysfunction, abnormalities, or scarring.

Photorefractive Keratectomy (PRK)

Another term for laser correction of nearsightedness.

PRK

Procedure involving the removal of the surface layer of the cornea (epithelium) by gentle scraping and use of a computer controlled excimer laser to reshape the stroma

Presbyopia

Age related inability to focus on near objects due to reduced elasticity of the lens; usually begins to surface between ages 40-45

Pupil

Hole in the center of the iris that changes size in response to changes in lighting

Radial and Astigmatic Keratectomy (RK and AK)

Radial incisions on the surface of the cornea correct nearsightedness; arcuate incisions are used to correct astigmatism.

Refraction

The change in the direction of light rays when they pass from one transparent medium to another of a different density. Errors in refraction occur when light rays do not come to a focus on the retina due to curvature of the cornea or lens, causing nearsightedness, farsightedness, or astigmatism.

Refractive Errors

Hyperopia, myopia and astigmatism

Retina

Layer of fine sensory tissue that lines the inside wall of the eye; captures images, much like film in a camera, and transforms images into electrical signals and sends to brain

Retreatment

A secondary refractive procedure performed after the initial one in an attempt to achieve better visual acuity

Sclera

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

Undercorrection

Complication of refractive surgery where the desired amount of correction is not fully achieved

Visual acuity

Clearness of vision; ability to distinguish details and shapes

Testimonials

Thank you so much Doc! When I first came to you I was 20/50 now I'm 20/10. I'm ready to have a great year!

Randy Foye
Pro Athlete, Utah Jazz #8

My experience at The Cornea and Laser Eye Institute has been amazing. All of the staff have been helpful and courteous...

Gillian
Phd Student, MMA fighter

Dr. Hersh and his staff were excellent. I was comfortable from the time I walked in until the time I left after the procedure.

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Pro Athlete, New York Giants Football