PRK (photorefractive keratectomy) was the first procedure performed using the excimer laser. It corrects vision by reshaping the cornea. The difference between LASIK and PRK is that with LASIK, a corneal flap is created and the laser is applied to the inner tissue of the cornea. With PRK, the epithelium (or outer skin of the cornea) is removed and a laser is applied to the surface of the cornea.
PRK can be used to correct low to high levels of nearsightedness, farsightedness, and astigmatism.
To treat nearsightedness, the steep cornea is made flatter by removing tissue from the center of the cornea. This moves the point of focus from in front of the retina to directly on the retina.
To treat farsightedness, the flat cornea is made steeper by removing tissue outside of the central optical zone of the cornea. This moves the point of focus from behind the retina to directly on the retina.
To treat astigmatism, the cornea is made more spherical — like a basketball instead of a football. This eliminates multiple focusing points within the eye and creates one point of focus on the retina. Astigmatism can be treated at the same time as nearsightedness and farsightedness.
Clear Lens Replacement
If you’re tired of wearing glasses but have been told that you’re not a candidate for LASIK, there is another vision correction option that may be right for you. It’s called Clear Lens Extraction and Replacement, and it’s designed especially for people who are over 40 and are not good candidates for LASIK. Clear Lens Extraction involves surgical removal of the eye’s natural or crystalline lens and replacement with an artificial (intraocular) lens to achieve clearer eyesight.
Unlike LASIK and other refractive surgery techniques that correct vision by changing the shape of the cornea, Clear Lens Extraction corrects your vision by changing the focusing power of the eye’s lens. To do this, we replace your natural lens with a new intraocular lens (IOL).
Like the lens of a camera, which focuses images sharply on the film, the eye’s lens focuses light and images on the retina at the back of your eye. With Clear Lens Extraction, your natural lens is replaced with an IOL selected to give you the best vision for your needs.
Clear Lens Extraction is well suited for people over 40 because that is the age that most of us begin to lose the ability to focus up close. This occurs when the natural lens becomes less flexible, and no longer accommodates as well to change its focus from distant to near vision. Then reading glasses or bifocals are needed for close work.