On the right, we show a normal eye before any type of refractive procedure. The dark purple layer on the outer part of the cornea is called the epithelium. This protective outer layer is always removed when performing PRK but is left intact with LASIK.
The device on the left is called a microkeratome. With it, the doctor slices the cornea from the side, producing a flap. A part of the device flattens the cornea during the slice, so as to create a flap of uniform thickness. It is at this stage of the procedure that the doctor must exercise extreme precision and caution to create a perfect flap.
On the right is a cross section view of the procedure performed by the microkeratome. The result is a uniform flap with a hinge, that the doctor rolls back to expose the inner layers of the cornea.
With the flap folded back, the doctor now makes the refractive correction on the inner layer of the cornea - done with excimer laser similar to PRK.
When treatment is complete, the flap is repositioned in its original position and the procedure is complete. The eye has a natural suction facility that keeps the flap firmly in place at this time. Care must be taken by the doctor to ensure an excellent fit when repositioning the flap. Because very little of the epithelium has been disturbed, patients report a high comfort level after the procedure.

Detailed description of the LASIK procedure
(complete with photos).

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For more information contact:
Dr. Murray McFadden
(BSc, MD, FRCS(C), Diplomate of the
American Board of Ophthalmology)
© Copyright 1996-2005 Murray McFadden MD, Inc.

Telephone: (604) 530-3332
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This page last updated on September 16, 2001.
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