LASIK glossary of terms P-W

P

Posterior chamber: Portion of the eye that is in front of the lens and behind the iris.

Presbyopia: An eye problem that usually starts after forty where eyes cannot focus at any distance and causes small print to be blurry.

PRK: A less invasive LASIK alternative where the stroma is reshaped with an excimer that is controlled by a computer.

Punctal cautery: A course of treatment for dry eye where the channels that drain tears are closed permanently.

Punctal plugs: A solution to dry eye that places tiny inserts in tear ducts to stop the drainage of tears.

Pupil: Center of the iris which is a hole that dilates to change its size in response to light. It will expand to let more light in when in low light environments and constrict to let less light in when lights are bright.

R

Refractive error: Any abnormality in the eye's ability to focus.

Refractive surgery: Surgery to repair any refractive error in the eye.

Retina: The tissue layer that lines the inner wall of the eye and reproduces images as electric impulses that get sent as signals to the brain.

Rod: A retina receptor that is sensitive to light allowing the eye to see in low light.

S

Sclera: The visible white portion of the eye in the front which surrounds the optic nerve in the back.

Snellen chart: The eye chart created by Herman Snellen to measure the acuity of the eye with letters, numbers, or symbols that are set up in rows that decrease in size as they get lower down the chart, and is now the standard used for eye exams.

Stroma: Cornea's middle portion

T

20/20 vision: A measurement that indicates normal or "perfect" vision. 20/20 is considered the average visual acuity for human beings.

U

Undercorrection: Risk factor of LASIK surgery when the vision problem is not fully corrected.

Uvea: Portion of the eye containing the iris, ciliary body and choroid.

V

Visual acuity: How sharp vision is according to the Snellen Chart.

Vitreous body: Portion of the eye between the retina and lens where the clear jelly like substance known as the vitreous humor is contained.

W

Wavefront: Technology used for eye mapping.