Types of Refractive Surgery
What’s the difference between different types of laser vision correction?
LASIK, PRK, LASEK, and epi-LASIK are four technique variations on a surgery with the same goal—reshaping the cornea to correct vision. The variations in the surgical techniques of each type are explained below along with another surgical method of vision correction.
All four types of laser vision correction enjoy high success rates and similar outcomes, so one is not superior to another. LASIK is the most popular laser eye surgery, but PRK and LASEK may be better for people with a high-degree of myopia or thin corneas.
The differences in the different laser vision correction procedures are:
- How the eye is prepped for the laser treatment.
- Whether the surgeon uses a flap.
- The thickness of the flap.
All the refractive surgeries entail reshaping the stroma layer of the cornea, the thickest layer of the cornea, which makes up 90% of corneal thickness. To get to the stroma layer an opening must be created.
In LASIK the opening contains the epithelium layer and the next layer (Bowman’s layer). The opening is left attached at one end and this “flap” of corneal tissue is moved out of the way while the stroma layer is remodeled. Once the remodeling is complete the flap is replaced over the altered stroma where it will stay because of the negative pressure of the cornea. The flap begins to heal immediately after being replaced and continues to heal for six to twelve months.
PRK does not create a flap. An opening is made through the epithelium and discarded. The stroma layer of the cornea is reshaped, and a “bandage” contact lens is placed on the eye to protect it from the eyelids during blinking and from any exterior sources of injury. The epithelium regenerates quickly and often repairs itself and grows back within 24 to 48 hours.
LASEK is similar to PRK in that it also lifts only a very thin epithelium layer instead of a thicker flap, but in LASEK the epithelial layer is replaced, rather than allowing the layer to self-regenerate as in PRK.
This is a variation of LASIK that uses only a thin epithelium layer, rather than the thicker layer in LASIK. The thin epithelium-only flap is replaced and a bandage soft contact lens is used to protect the cornea after the procedure.
For patients who are not good candidates for a laser vision corection because their nearsightedness, farsightedness, or astigmatism is severe could benefit from implantable lenses. These are the same intraocular lenses that are used for cataract surgeries. The lenses come in a variety of types such as monofocal, multifocal, extended depth-of-focus, and toric lenses for astigmatism.