LASIK: Glossary of Terms

Opthalmologist performing a routine eye exam

For people who are thinking of laser eye surgery, it’s a good idea to get acquainted with the various terms related to the procedure. In this glossary of terms, you will find descriptions of some common terms associated with LASIK surgery. Take a look at this list before you go to the ophthalmologist.


Astigmatism: The optical defect in which the eye fails to focus light to a point on retina. It’s caused by irregular curvature of the lens or cornea.

Cornea: The part of the eye which is transparent and covers the anterior chamber, iris, and pupil.

Diopter: The unit which measures the optical lenses. Its value is equal to the inverse of focal length.

Dry Eye Syndrome: The medical condition, in which, the patient fails to produce tears. Some patients suffer from Dry Eye Syndrome, when LASIK eye surgery is not successful. The patient may get symptoms such as burning sensation and pain in the eyes.

Endothelium: The cells which line the inner surface of blood vessels.

Epithelium: The cells which line the cornea, preventing infections to eyes.

Excimer Laser: The laser rays used to take out corneal tissues in LASIK surgery. The laser energy is reduced through a mixture of gases in excimer laser.

Hypermetropia (also known as farsightedness and hyperopia): It refers to the condition when the person fails to see distance object clearly.

Haze: The clouding of the cornea which causes the person to feel as though they are looking through fog or smoke.

Iris: The tissue found between the cornea and the lens.

Keratectomy: The process which involves the removal of corneal tissues to improve focus.

LASER or “Light Amplification by the Stimulated Emission of Radiation”: It’s a form of radiation which helps in vaporizing tissues.

Laser Keratome: This is the apparatus for the creation of the corneal flap.

LASIK or “Laser Assisted in Situ Keratomileusis”: LASIK is a form of refractive surgery used to create the cornea flap and reshape the cornea. This is done with the microkeratome.

Lens: It helps to improve the focusing power of the eye, enabling clearer vision. There are different types of lenses such as concave and convex lenses.

Microkeratome: It’s the device with oscillating blade used during LASIK eye surgery to create corneal flap.

Myopia (or Nearsightedness): The condition, in which, the patient cannot perceive distant objects clearly.

Ophthalmologist: A specialist in medical treatment and surgery of visual disorders.

Photorefractive Keratectomy (or PRK): The procedure whereby the layer on the epithelium’s surface is scrapped using computer controlled mechanism.

Pupil: Refers to the hole found in the iris’ center. It changes according to the light’s intensity.

Radial Keratotomy (or RK): The procedure used to correct nearsightedness whereby the cornea is flattened with radial cuts.

Sclera: The outer portion of eye which offers protection for the eyeball. It’s the white of the eye.

Stroma: The cornea’s thickest stratum of tissue.

Vitreous Humor: This is the transparent fluid which fills the centre of eyeball.

Wavefront-guided LASIK: The method which uses computer controlled excimer laser and wavefront sensors to get accurate measurement to provide optically perfect eyes.

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