Vision Disorders

A

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.

Acuity – sharpness, or clearness of vision.

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.

B

Baush & Lomb – a popular manufacturer of excimer lasers for vision correction

Bladefree LASIK – when a LASIK flap is created with a femtosecond laser. Brands include: Ziemer, Victus (Bausch & Lomb) and Intralase®

C

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.

Cataract – clouding and opacification of the eyes natural crystalline lens. Cataract surgery, involving removal of this lens, is required to regain vision.

D

Diopter - the measurement of refractive error. A negative diopter value signifies an eye with myopia and positive diopter value signifies an eye with hyperopia.

Dry Eye Syndrome - when the eyes do not produce enough tears to keep the eye moist and comfortable. It is a common condition. Symptoms of dry eye include pain, stinging, burning, scratchiness, and intermittent blurring of vision.

E

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

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.

F

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.

G

Glare - bright light scattering that decreases vision.

H

Halos - optical imperfections in or in front of the eye cause rings around lights.

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

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

Hyperopia - the inability to see near objects as clearly as distant objects, and the need for accommodation to see distant objects clearly.

I

Intralase Technology – A brand name for blade-free flap creation with a femtosecond laser, this is used instead of a microkeratome, another version of similar technology is Ziemer

Iris - the colored area immediately in front of the lens.

K

Keratectomy - the surgical removal of corneal tissue.

Keratotomy - a surgical incision (cut) of the cornea.

Keratitis - inflammation of the cornea.

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

Keratomileusis - carving of the cornea to reshape it.

L

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.

LRI - Limbal relaxing incisions are made around the edges of the misshapen cornea, allowing vision correction specialists to flex and reshape the cornea, rounding the tissue and thus improving vision. During an LRI procedure, or limbal relaxing incision, the surgeon cuts the limbus, which allows the cornea to become more rounded when it heals. These incisions are also called peripheral corneal relaxing incisions.

M

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.

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.

N

Nearsightedness – The clinical term being myopia

O

Ophthalmologist - A medical eye doctor capable of performing eye surgeries.

Optometrist – a primary 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.

P

PRK - the acronym for photorefractive keratectomy which is a 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. This is often called Advanced Surface Ablation

Presbyopia - the inability to maintain a clear image (focus) as objects are moved closer. Presbyopia is due to reduced elasticity of the lens 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.

R

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.

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.

S

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.

V

VISX – A popular manufacturer of Laser Vision Correction excimer lasers

W

Wavefront - a measure of the total refractive errors of the eye, including nearsightedness, farsightedness, astigmatism, and other refractive errors that cannot be corrected with glasses or contacts.