Ablation
This term applies to the vaporization of corneal tissue caused by the excimer laser.

ACS
Anterior ciliary sclerotomy – intended to accomplish the same thing as SEB’s but by making radial incisions in the white of the eye (sclera). Fairly rapid and predictable effect but very short-lived; numerous efforts to try to prolong the effect have failed.

ACS is also an abbreviation for Automated Corneal Shaper, the name of the first generation microkeratome originally used in LASIK.

AK
Astigmatic Keratotomy – an incisional procedure, it was often combined with RK to correct astigmatism. A variation (limbal relaxing incisions – LRI) is sometimes performed in conjunction with cataract surgery to reduce pre-existing astigmatism.

Allegretto
A prolate-based laser system manufactured by Wavelight. Manufactured in Germany and first approved in this country in 2004.

ASA
Advanced surface ablation – another term for PRK. Usually implies the use of some sort of newer technique for epithelial removal (e.g., alcohol) and haze prevention.

Astigmatism - regular
Refractive error in which light rays are focused at different points in the eye’s optical system. Usually a result of the cornea being shaped more like part of a football than part of a basketball and thus having areas of different curvatures leading to the different focal points. Usually present to some degree since birth, but can be induced by certain ocular surgeries and/or trauma. (see irregular astigmatism)

Autonomous
An excimer laser company which evolved from Summit technologies, the first recipient of FDA approval for PRK in 1995. First company to achieve FDA approval for wavefront-driven ablation in late 2002.

CK
Conductive Keratoplasty – a treatment originally designed to treat hyperopia, but more recently used for producing nearsightedness in one eye for monovision. The effect is accomplished by steepening the cornea by placing marks in the midperipheral cornea with a special type of radio frequency probe. Each mark produces collagen shrinkage and thereby, corneal steepening. Although seen to be less invasive than LASIK, it is less accurate, less stable and cannot correct astigmatism (in fact may produce new astigmatism); but it may produce a form of monovision that may work well for selected patients. Because of regression, it often needs to be repeated.

Custom
A generic term applied to excimer laser treatments that are wavefront-driven or wavefront-guided.

CustomVue
The proprietary name VISX gives to their system of wavefront-guided treatment.