LASIK vs PRK: Differences and benefits with each

Posted by Tejus Parikh on September 17, 2009

Disclaimers first. This post is not medical advice and I’m not a medical professional. Always consult with your eye-care professional about anything involving your vision. Always. With that out of the way, I want to answer a question that I’ve gotten a lot recently. Almost everyone has heard of LASIK (laser-assisted in situ keratomileusis). Most companies and doctors offering corrective surgery advertise this procedure. Not as many people have heard of PRK (Photorefractive keratectomy). PRK is the procedure that Sonali had done a few weeks ago. LASIK is what I will be having done tomorrow. Both are corrective, out-patient eye surgeries, and eliminate the need for the patient to wear corrective equipment, such as glasses or contacts. The recommended procedure depends on many factors. This post seeks to explain some of these differences.

What they are

LASIK is the more common procedure. In this procedure, a surgeon cuts a flap in the cornea to expose the area on which the laser operates. Once the laser has finished, the surgeon replaces the flap, which stays in place naturally. The creation of this flap leaves a permanent scar that is visible in close examination (when the eye-doctor shines the bright light in your eye). PRK involves the removal of the top layer of quickly regenerating cells in order to reach the layer that can be effected by the laser. There is no flap. Over time, new cells replace the ones removed and the eye returns to its natural strength. Both surgeries take only a few minutes in the operating room.

One over the other

LASIK is the preferred procedure, because the patient is able to function normally within a few days. As long as the patient refrains from rubbing their eyes, the risk of flap displacement remains low. However, the creation of this flap permanently reduces the strength of the cornea and increases the risk of flap displacement in the case of trauma. In situations where the patient’s career exposes them to abnormally high levels of risk for head trauma, such as mixed martial artists, astronauts, and professional deep-sea divers, PRK is the only viable option. Even if you don’t have an exciting career and are a normal software professional, the doctor may require PRK if the corneal tissues lack the necessary thickness. This was the case with Sonali. Also, if you’ve had LASIK, but your vision has degraded, the follow up procedure will be PRK. If PRK was not so inconvenient, almost nobody would get LASIK.


The obvious benefits are you don’t have to wear glasses or contacts. If you’re someone like me, with absolutely horrible vision, glasses are not really a viable option. Even the most expensive and thinnest lenses have noticeable levels of diffraction for any object not in the center of my field of view. While tolerable during the day or at home, being outside at night is frustrating experience. Contacts are far superior for vision, but they are inconvenient for traveling. There are other risks as well, including the increased risk of eye infection and eye-fatigue caused by the lack of oxygen to the eyeball.

Major Downsides

The risk with both these surgeries is that you may never regain the same corrected vision. There’s a chance of halo’s, glare and reduced night vision. With Lasik, the most terrifying risk is that your eye might fall apart. It’s not very likely long-term, but highly likely if you rub your eyes within a month of the procedure. PRK is a far safer procedure, but requires much more time to heal. The same level of vision correction that is enjoyed by a Lasik patient in 48 hours takes 6 weeks to achieve with PRK. It will take at least a week for a PRK patient to be able to carry out normal tasks. The first week after PRK also involves more discomfort and pain. Dry eyes are also a problem. There are other downsides and risks. Again, please consult your doctor.

Why does PRK take longer?

Instead of resealing a cut, the eyes of PRK patient have to re-grow tissue that has been removed. This has two side-effects. One is that there are more exposed nerve-endings being stimulated, causing the pain and discomfort experienced by PRK patients. The second is that the cells regrow, it takes time for them to regain uniform density, resulting in blurry vision. There is no way for your brain to focus the image because light is not being aligned correctly, but during this period the patient does not have a prescription. Corrective lenses will not help.

Is it worth it?

I dunno, too early to tell. Check back in a few months. This is just an overview, since many people are unaware of the existence of a second procedure. There is much more information out on the web. Please post any questions in the comments.

Tejus Parikh

Tejus is an software developer, now working at large companies. Find out when I write new posts on twitter, via RSS or subscribe to the newsletter: