PRK was the first method that used the precision of the excimer laser to reshape a human eye during FDA monitored clinical trials in New Orleans in 1987. The first person to have PRK surgery started with an uncorrected vision of 20/200 (legal blindness) and was able to achieve 20/20 vision without glasses after the surgery. They continue to see 20/20 without glasses to this day.  In the 21st century, PRK has largely been replaced by LASIK or LASEK surgery due to their advantages of less pain, faster return to excellent vision, and shorter course of eyedrop usage after the surgery

Steps to PRK

1. Under the LADARVision excimer laser, the patient’s eye is numbed using anesthetic drops, and cleaned with sterile tear solution
2. The eye is tracked to freeze it on the LADARVision computer screen, and the area that will be reshaped is superimposed.
3. The cornea surrounding the area to be reshaped is marked, and the epithelium is removed within this area.
4. The LADARVision tracking / flying spot laser is then used to precisely reshape the outermost stromal layer of the cornea.
5. After the laser reshaping is complete, the doctor will clean the surface of the newly shaped cornea.
6. A bandage contact lens is then applied to the eye which allows the epithelium or skin of the cornea to begin to heal over the next 3 three to five days. Eyedrops are started immediately.
7. Unlike LASIK, the patient does not require eye shields to protect a flap.  The epithelium of the cornea regenerates on its own

Refractive Errors

The eye is like a camera. In a camera, light passes through a lens system back onto the film. The cornea and lens are at the front of the eye (anterior chamber) and are similar to a camera’s lens system. The retina is located at the back of the eye (posterior chamber) and is similar to the camera’s film. In the normal eye, light rays of an image pass through the cornea and the lens and are focused directly on the retina to produce a clear image.

Myopia (Nearsightedness)

In a myopic eye, the light rays are passed through the cornea and lens but the point at which they converge (focus) is in front of the retina, not on the retina. This configuration allows clear images of near objects but not those that are far away. Non-surgical treatment options for myopia include glasses and contact lenses. Surgical treatment options include ALK, clear lens extraction, LASEK, epi-LASIK, phakic IOL and RK. While there are numerous surgical options available, not all individuals are good candidates for specific procedures.

The Cornea

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The cornea is the clear covering of the front of the eye which bends (or refracts) light rays as they enter the eye. For clear vision to occur, the cornea must have the correct shape and power to focus incoming light rays precisely on the retina at the back of the eye. If the cornea is too steep, flat or irregular in shape, it cannot bend light at the angle needed to focus on the retina. As a result, eyeglasses or contact lenses may be needed to refract the incoming light rays at the angle needed for clear vision. In a nearsighted eye, for example, the cornea’s shape causes incoming light rays to focus in front of the retina.

All corneal modification procedures are intended to alter the curvature of the cornea so that incoming light is refracted at an angle that allows it to focus precisely on the retina. This may eliminate the need for eyeglasses or contact lenses, or reduce the power of prescription lenses needed.

Those interested in any of the corneal modifications should first have a comprehensive eye examination to evaluate their eye health and determine their vision needs.

In the nearsighted eye, the cornea’s shape causes incoming light rays to focus at a point in front of the retina.

A cornea of the appropriate shape bends (or refracts) incoming light rays so they focus precisely on the retina at the back of the eye.