PRK
Photorefractive Keratectomy (PRK) uses a laser to sculpt the surface of the cornea. This contrasts with LASIK, which sculpts tissue deeper within the cornea, under a corneal flap.
PRK is useful for treating low to moderate levels of myopia or hyperopia with and without astigmatism. It is often the laser vision correction procedure of choice for people with thinner corneas and for individuals who may have certain corneal dystrophies, certain corneal scars, or a condition called "recurrent corneal erosion". Some refractive surgeons prefer PRK over LASIK for all their patients because there is no risk of a flap complication with PRK.
PRK differs from LASIK only in the first step of the procedure. In PRK, instead of creating a corneal flap, the surgeon completely removes the thin outer layer of the cornea (called the epithelium) over the treatment area. The second step of PRK is identical to LASIK: an excimer laser is used to reshape the underlying corneal tissue.
After the laser ablation, a soft contact lens is placed over the eye as a bandage while the corneal epithelium grows back in place, which usually takes about 3 to 5 days. During this period, the patient usually experiences mild to marked discomfort with blurry vision. Because of the greater amount of tissue healing that needs to take place after PRK, it can take from a week to ten days before vision is clear and stable after the procedure.
The post-operative discomfort and longer time required for corneal healing and visual recovery are reasons why PRK is not as popular as LASIK. Still, in some cases PRK offers advantages over LASIK, and the final visual outcomes of PRK are usually equal to those of LASIK.
EPILASIK
EPILASIK is an innovative new procedure designed to restore natural vision with the help of an epikeratome. The Epi-Lasik surgeon uses an epikeratome, a separator that creates an epithelial sheet, to make a thin flap in the epithelium. The excimer laser beam is then applied under the epithelial flap to successfully correct refractive errors and restore clear vision.
Advantages of EpiLASIK
- Overcomes the limitations of LASIK
- The treatment of choice for eyes with high powers
- Treatment of choice for thin corneas
- Very safe for steep and flat corneas
- Patients who are not eligible for LASIK
LASEK
Laser epithelial keratomileusis, or LASEK, is a newer form of laser vision correction that combines many of the benefits of the two most commonly performed procedures -- LASIK and PRK. It is used to treat astigmatism, nearsightedness or farsightedness. In LASEK, the epithelium, or outer layer of the cornea, is cut not with the microkeratome cutting tool used in LASIK, but with a finer blade called a trephine and a 20% alcohol solution.
Advantages of LASEK
- Complications associated with cutting and reattaching the flap in the cornea as is done in LASIK are avoided.
- LASEK causes dry eye less frequently than LASIK.
Disadvantages of LASEK
- Longer visual recovery time compared to LASIK. Many LASEK patients will not fully recover functional vision for 1 to 2 weeks while their eye heals, which is similar to the healing time experienced in PRK. LASIK patients often have good vision by the day after surgery.
- LASEK may cause more pain and discomfort than LASIK , but less pain than PRK. Most LASEK patients say the discomfort lasts about 2 days or less.
- Patients need to wear a "bandage contact lens" for about 3 or 4 days after LASEK to serve as a protective layer between your blinking eyelids and the treated eye surface, which is not necessary after LASIK.
- Patients must use topical steroid drops for a longer period than that used after LASIK.
Side effects
- Sensation of having a foreign object in your eye (can last anywhere from 1 to 4 days)
Dry eyes, requiring the use of moisturizing drops (up to 6 months)
- Tests for refractive proedures
- Detailed medical history will be taken and eye tests will be carried out. Tests will include corneal thickness measuring, refraction, and pupil dilation, retinal check up, checking of eye pressure, corneal topography.
- If you wear rigid gas permeable contact lenses, you should not wear them starting three weeks before the date of your surgery. Other types of contact lenses shouldn’t be worn for at least ten days prior to surgery. Be sure to bring your glasses so your prescription can be reviewed.
- On the day of your surgery, eat a light meal before coming and take all of your prescribed medications. Do not wear eye makeup or have any bulky accessories in your hair that will interfere with positioning your head under the laser.
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