PRK (Photorefractive Keratectomy) and epi-Lasik
PRK was the first procedure done with the excimer laser. The surgeon first removes the epithelium covering the cornea, then the laser reshapes the surface of the cornea by ablating (removing) some of the corneal tissue. The epithelium then grows back over the new corneal surface.
Epi-Lasik is basically the same procedure as PRK, but we replace the epithelial cells after the laser ablation is finished. Epi-Lasik gives a shorter recovery time for patients with higher levels of nearsightedness who have PRK.
Most patients can have PRK, epi-Lasik, or Lasik. The advantage of PRK and
epi-Lasik is that the procedure is done right on the surface of the cornea, so
there is no flap made. Therefore there are fewer precautions needed in the
post-operative period. The disadvantage of these procedures is that the recovery
of vision is longer, as the surface of the cornea needs to heal and become
smooth before sharp vision returns.
Lasik
This is the excimer laser procedure developed to avoid some of the discomfort and slower recovery of vision of the PRK procedure.
The PRK procedure reshapes the surface of the cornea, whereas in Lasik, the laser reshaping is done within the cornea, under a partial thickness layer of corneal tissue. This is done by creating a thin partial thickness layer of cornea, with an instrument called a microkeratome. This layer, or flap as it is called, is then moved out of the way while the laser treatment is performed. The flap is then put back in its original position, where it assumes the new curvature of the remodeled cornea beneath it.
Because the cornea still has its original surface, the vision returns quickly, and discomfort is minimal.
CK – Conductive Keratoplasty
CK is a relatively simple operation done in the office to reduce the need for reading glasses in the ‘over 40-something’ age group. No tissue is removed, no laser or cutting is done. An ultra-thin probe activated by radio waves will reshape the cornea of one eye to improve the reading vision in that eye. This results in a type of monovision. The procedure is personalized for each candidate to try to reduce your dependence on those bothersome reading glasses.
RK - Radial Keratotomy
This was the first refractive surgery procedure introduced in the United States, in 1978. Millions of people have had this procedure to correct nearsightedness. Making incisions in the cornea with a sharp blade changes the curvature of the cornea. This procedure weakens the cornea, and in some cases causes the cornea to become progressively flatter over a long period of time. RK is currently appropriate for only low levels of nearsightedness, and few surgeons perform the procedure any longer.
Lens Implant
For those persons so nearsighted or farsighted that the laser cannot correct their vision, more complex procedures are available. The lens of the eye can be surgically removed and replaced with a lens implant, which is essentially the same as a cataract operation. Recently, lens implants have been developed that can be surgically placed inside the eye without removing the human lens. These procedures are newer, and are chosen on a very individualized basis.
