Encyclopedia - Microkeratome

A microkeratome is a surgical instrument used for shaving and/or reshaping the front surface of the cornea. The most common use of the microkeratome is in the refractive eye surgery procedure called laser in-situ keratomileusis (LASIK). A microkeratome is also sometimes used during the corneal transplant procedure.

The microkeratome works like a miniature carpenter's plane and contains a disposable blade that is preset according to the thickness of the cornea. The instrument operates in conjunction with a suction ring that holds the eye perfectly still and, when activated by a vacuum tube, raises and flattens the cornea so it can be reached easily for the actual shaving procedure.

In a LASIK procedure, the surgeon uses the microkeratome and the Excimer laser to produce a refractive correction. The microkeratome travels most of the way across the cornea, but is automatically stopped to prevent the tissue from being cut off. This leaves a hinged flap that is gently lifted aside to expose the underlying corneal tissue. A computer-controlled Excimer laser is then used to sculpt the underlying tissue, reshaping the eye to correct for various refractive errors. The flap is folded back in place and left to heal, a process that usually takes from 24 to 48 hours.

The microkeratome is sometimes used during a corneal transplant procedure to remove any severely diseased or damaged corneal tissue prior to the transplant. The microkeratome is used to make the exact same incision in the donor corneal tissue. This creates a precise fit when the new tissue is placed on the eye.