I can see clearly now - An introduction to LASIK, LASEK, and PRK

Sarah Ma

Laser eye surgery has become an increasingly common procedure done in individuals to correct for nearsightedness (myopia), farsightedness (hyperopia), or astigmatism. Individuals with normal vision are able to focus light rays onto their retina to form an image that can be received by the brain. On the other hand, patients with refractive errors often have imperfect curvature of their eye, leading to light being focused before or past the retina, ultimately causing vision problems.

In general, patients who wish to receive vision corrective surgery must meet specific criteria that will be assessed by an ophthalmologist or optometrist.

Some criteria are:

• Must be over 18 years of age and ideally over 21 years of age

• Should not have had a change in prescription in the last year

• Good eye health (especially including the cornea)

• Should not have refractive error that is too severe

• Should not have certain health conditions such as dry eyes, glaucoma, frequent eye infections, diabetes, etc

• Should not be pregnant

Some of the most common corrective surgeries being performed are LASIK, LASEK, and PRK. All three methods commonly involve the use of a specialized keratome to remove part of the corneal layer so that an excimer laser can be used on the stroma to adjust curvature.

Of the three surgeries, PRK (also referred to as Photorefractive keratectomy) was first introduced in 1987 and is known to be the precursor to LASIK surgery. PRK involves the use of alcohol debridement to initially loosen the epithelium of the eye. The ophthalmologist will then use a surgical instrument to carefully peel away the epithelial layer and Bowman’s membrane to reveal the stroma of the eye underneath. Using an excimer laser, they will reshape the cornea. A protective contact lens may be placed on the eye once the procedure is completed. As this method completely removes part of the epithelial layer, vision will be completely restored approximately one month post surgery.

LASIK surgery (Laser-assisted in situ keratomileusis) was first used in 1990 and was considered to be an updated version of PRK. As opposed to PRK, it uses a microkeratome or a femtosecond laser to cut a small flap of the corneal epithelium and does not require the use of alcohol. The doctor will gently fold this flap back to expose the surgical site of the corneal layer, which can be ablated using the excimer laser. Once completed, the flap will be folded back onto the eye and acts like a natural bandage to the surgical site. As a result, LASIK is considered to be one of the safest corrective surgeries and rarely causes complications. Patients who receive LASIK surgery will typically regain vision within two to five days.

Finally, LASEK is the most recent of the three laser eye surgeries that was introduced in 1996 and combines principles of PRK and LASIK. Similarly to PRK, an alcohol solution is used to separate the epithelium from the stroma. Where PRK completely removes the epithelial layer from the surgical site, LASEK creates a flap similarly to LASIK, however the flap made in LASEK surgery does not include part of the stroma as LASIK does. Again, following the use of the excimer laser to reshape, the flap is put back onto the surgical site to act as natural protection to the site. LASEK has a similar rate of healing to LASIK, and takes four to seven days to restore vision.

The three methods discussed can have varying healing time depending on the patient’s refractive error, size of the surgical site, and overall health but not one method is superior to another. Though the epithelial layer of the eye may heal within a few days, vision correction may take weeks to months to become noticeable. Laser eye surgery rarely has major side effects, but some of the most common ones are dry eyes, blurry vision, halo vision, and light sensitivity. Any side effects that occur may be either temporary or permanent depending on the person. So, if you or someone you know would like to see clearly without the use of your glasses or contact lenses, consult your health provider about receiving laser eye surgery!