LASIK, PRK and Other Refractive Procedures
LASIK (laser in-situ keratomileusis)
LASIK is a surgical technique that uses precise excimer laser energy to alter the refractive status of the eye. This is an elective procedure performed to decrease or eliminate the need for glasses or contact lenses. It can correct nearsightedness, farsightedness, and astigmatism. LASIK consists of first making a corneal flap (typically with a laser rather than a blade). After the flap is created, the laser removes small amounts of underlying tissue from the exposed cornea. The flap is then carefully placed over the eye and repositioned to complete the surgery.
Advantages of LASIK are quick recovery time and minimal discomfort. Disadvantages are that creation of the flap involves surgery deeper into the layers of the cornea which can weaken corneas in patients whose corneas are thin. Creation of the flap can also worsen dry eye symptoms in patients who are predisposed to the problem. Regardless of the type of refractive surgery, there is always a chance that retreatment may be necessary. This is an outpatient procedure.
PRK (photorefractive keratectomy)
PRK is a surgical technique that uses precise excimer laser energy to alter the refractive status of the eye. This is an elective procedure performed to decrease or eliminate the need for glasses or contact lenses. It can correct nearsightedness, farsightedness, and astigmatism. In contrast to LASIK, PRK avoids the creation of a corneal flap. PRK involves mechanical removal of the surface cells. The laser is then used to remove small amounts of tissue from the front surface of the cornea. This leaves a greater portion of the cornea untouched, which can be important in patients with thin corneas. Advantages of PRK are less risk of complications (since no flap is created) and less affect on dry eye symptoms in patients who are predisposed to the problem. Disadvantages include mild discomfort and less rapid visual recovery (7-10 days as opposed to 1-3 days with LASIK). Regardless of the type of refractive surgery, there is always a chance that retreatment may be necessary. This is generally an outpatient procedure.
Peripheral Corneal Relaxing Incision (PCRI) (also known as limbal relaxing incision, LRI)
PCRIs are fine microscopic incisions made just inside the cornea. The purpose is to improve the clarity of vision without glasses. These are performed electively to correct certain types of astigmatism. Astigmatism occurs when the cornea has different curvatures in different directions. PCRIs flatten the steepest part of the cornea in effort to make a cornea more uniform curvature. The goal is to make the curvature more spherical like a basketball as opposed to the shape of a football. This is often done in combination with cataract surgery.
Implantable Collamer Lens (ICL) Implantation
In patients who are not candidates for laser excimer surgery such as LASIK or PRK, ICL implantation can be performed. Often a laser procedure is performed one week before the surgery to prevent glaucoma post-operatively. Then, the outpatient procedure is performed by implanting this flexible lens implant in front of the patient’s natural lens. This is an elective procedure performed to decrease or eliminate the need for glasses or contact lenses.
Refractive Lens Exchange (RLE)
In patients who are not candidates for laser excimer surgery such as LASIK or PRK, RLE can be performed. This elective procedure is performed in patients who have a clear lens (i.e. no cataract) but want to reduce or eliminate their dependence on glasses and contact lenses. This involves removing the clear lens using phacoemulsification, as in standard cataract surgery discussed elsewhere on this site. An intraocular lens implant is then placed. The various types of IOLs available are discussed elsewhere on this site.