Atopic or Atopy - conditions associated with allergy like: asthma, eczema, hayfever

Decentration - off centered position

Donor tissue - the part of the cornea that is transplanted.  The eye tissue removed upon a donor's death for transplantation.

Epikeratophakia - a thin disk of donor cornea is sutured to the patient's cornea after the patient's epithelium (top layer) has been removed to add thickness.

Filaments - string or ribbon-like threads of epithelial cells and mucous that attach to the outer surface of the cornea.

Graft-host junction - where the donor cornea and patient's cornea meet and are sutured.

Host tissue - cornea of the patient, the part of the patient's cornea that is left in place when the central portion is removed to be replaced with the donor tissue.

Hydrops - a condition in which the back surface of a thin cornea ruptures, allowing fluid to waterlog the cornea, making it opaque instead of clear.

Keratic precipitates - (KPs) inflamatory cells that adhere to the innermost layer of the cornea and signal a rejection episode.

Kerato - (prefix) pertaining to the cornea

Keratometer - a device used to measure corneal curvature.

Keratomileusis - patient's cornea is removed, frozen, reshaped on a computer assisted lathe- then returned to it's original position.

Keratophakia - the surgical removal part of the surface of the cornea and its replacement with a donor cornea that is reshaped and transplanted to the patient's cornea.

Keratoplasty - (corneal transplant) is the excision of all layers of the central portion of the cornea and replacement with a clear cornea from a human donor.

Lamellar Keratoplasty - (Non-Penetrating Keratoplasty) the outer two thirds of the cornea is removed and replaced with donor cornea.

LASIK - "laser assisted in situ keratomileusis." It is a refractive surgery procedure for the correction vision in which a thin layer of the front of the cornea is lifted surgically and the underlying cornea is reshaped using an excimer laser. It is not a procedure applicable to keratoconus.

Penetrating Keratoplasty - (corneal transplant) full thickness layers of the cornea are replaced with a full thickness layer from a donor. The entire thickness of cornea is removed and replaced by full thickness donor corneal tissue.

Sutures - stitches, usually of a nylon material that are used to sew the new cornea tissue in place.

Trephine - a surgical instrument, a cutting tool, used to make a precise circular cut in tissue.