What’s the difference between LASIK and PRK?

If you are tired of glasses and contact lenses and just want to wake up and see, you are likely aware of the very popular LASIK procedure, but what about its “cousin” procedure, PRK?

One of the more common questions that patients have for the LASER Vision Correction Specialist Doctors at 20/20 Institute is about the differences between LASIK and PRK.  Our doctors routinely perform both procedures with excellent results, and understand that what each patient really wants to know is which procedure would be the best for them.

So, we will discuss the two procedures so when you visit 20/20 Institute for your complimentary consultation, you’ll have a great background of understanding to help the discussion with our doctors about what is best for you!

How are LASIK and PRK similar?

Most eye care professionals agree that LASIK and PRK are both considered safe and effective Laser Vision Correction procedures provided of course that the patient is a good candidate.  Both procedures use an excimer laser to correct vision and because they have a similar method of achieving improved vision without glasses or contacts, the final visual result for patients tends to be very similar.

In the majority of cases, the excimer laser technology your surgeon uses has the greatest impact on achieving 20/20 vision than whether the correction is done with the PRK procedure vs the LASIK procedure.

LASIK and PRK have similar results because they both reshape the cornea.  The cornea is the structure in the front of the eye responsible for most of the eye’s focusing ability (it’s the part of the eye where a contact lens is placed).

Put simply, a person wears glasses or contact lenses due to a mismatch between the length of the eye and the shape of the lenses, primarily the cornea.  If the cornea is the wrong shape for the patient’s visual system, the patient has blurry vision.  The excimer laser essentially vaporizes microscopic amounts of tissue in a precise, customized pattern to change the cornea’s shape to improve the patient’s vision.

A basic understanding of the cornea is helpful to understand more about how LASIK and PRK work.  First, the cornea has five layers.  The main layer, called the stroma, is the middle layer of the cornea, comprises 90% of its thickness, and is made of collagen tissue fibers arranged in a way that makes the cornea translucent and have a high refractive index – both important characteristics of a focusing lens.  The outermost layer of the cornea is a layer of translucent epithelium tissue (skin) to protect the cornea from the environment.

Just like skin on other parts of the body, the cornea’s epithelial layer grows back if it is damaged or removed, however the collagen tissue that makes up the stroma does not.   In LASIK and PRK procedures, the excimer laser sculpts the stroma layer, resulting in a permanent change to the shape of the cornea.  When the shape of the cornea is changed properly, the result is that the light that enters the patient’s eye is focused more properly for improved vision without glasses or contact lenses.

How is LASIK and PRK different?

While LASIK and PRK have comparable results, they are performed differently. That gives each procedure its own set of advantages and disadvantages.  In certain cases, a patient may be only a candidate for LASIK or only a candidate for PRK.  In other situations, the patient can be a candidate for both and may choose the procedure they prefer.

The difference is the way that the LVC Surgeon accesses the cornea to reshape it with the excimer laser.  The epithelium (skin) tissue that covers the cornea must be removed or temporarily moved out of the way before the excimer laser can sculpt the cornea.  The method that removes the tissue is called PRK, and the method that temporarily moves it out of the way is called LASIK.

LASIK Procedure Explained

With LASIK, the surgeon fashions a LASIK “flap” or “cap” using a specialized surgical instrument to temporarily move the epithelial layer out of the way.  The LASIK flap contains the epithelial layer and a thin portion of the stromal layer and remains attached to the rest of the cornea.  The surgeon lifts the flap and folds it out of the way to expose a lower layer of the cornea to be sculpted with the excimer laser.  After the reshaping is complete, the surgeon positions the flap in its original position and the healing process begins.

Modern LASIK uses a femtosecond laser to separate tissue for the flap creation. Early methods of LASIK used a mechanical device that used a blade to create the flap.  Because the Bladeless (laser) method eliminates the possible side-effects and complications associated with creating the flap with the bladed instrument, all LASIK procedures from the 20/20 Institute are performed with a laser to create the flap.

During flap creation, the patient experiences pressure on the eye (numbed with anesthetizing eye drops) and dim or dull vision for about 45 seconds.  This is usually the most uncomfortable part of the 5 minute-per-eye LASIK procedure.

When the procedure is complete, the patient can see.  For most patients it looks as though they have their eyes open under water – it is a rather foggy view of the world, but typically dramatically better than the blurry world the patient had before.  Visual recovery is generally very rapid, and most patients experience little to no discomfort during the initial healing time.  Most patients have 20/20 or better vision without glasses or contacts by the morning after their procedure.

Usually the worst part of post-op LASIK recovery is about three hours of sometimes intense irritation or burning – almost like it feels if you have your eyes open in a chlorinated pool.  Most patients fall asleep shortly after leaving our office or arriving home (thanks to a little sedative pill given prior to the procedure), and they sleep right through that 3 hours of irritation and wake up feeling pretty comfortable.  For most patients, slight irritations like having an eyelash in the eye are the only sensations felt after that nap.  Artificial tears make those sensations go away and they typically resolve on their own within three or four days after LASIK.

PRK Procedure Explained

With the PRK procedure, there is no flap created.  Instead, the surgeon gently removes the epithelial tissue layer of the cornea, and then applies the excimer laser to the exposed cornea for the reshaping step.  When the reshaping is complete, a contact lens bandage (a contact lens with essentially no prescription power) is placed over the cornea to allow the skin to grow back underneath.

Removing the epithelial layer is rather quick, taking less than 30 seconds.  Surgeons vary in their technique but regardless of the technique used, the patient may experience a small amount of pressure on the eye and dim vision when the surgeon gets in the way of their vision.  The reshaping step is next, and usually takes less than 30 seconds as well.

When the reshaping is complete, the patient receives the contact lens bandage and a few eye drops.  After the procedure is completed, the patient can see fairly well, typically dramatically better than before the procedure without glasses on.  That vision is short-lived however, as vision tends to get worse before it improves as the eye heals after PRK.

Healing and subsequent visual recovery after PRK takes longer because the epithelial tissue has to heal and become as regular and smooth as it was before removal.  Full visual recovery typically takes about thirty days and has three general stages: initial healing, bandage contact lens removal, and full healing.

The patient wears the contact lens bandage for about 4-5 days as the epithelial tissue undergoes the initial healing phase where it seals the surface from where it was removed.  During this time, the patient’s vision is typically fairly blurry and there is usually a relatively high amount of discomfort and light sensitivity.  20/20 Institute doctors will prescribe a few medicines that significantly help with the discomfort, but it usually lasts about 3 to 4 days, improving slightly day after day.  Most patients are not comfortable driving a car during this time, so planning with work and life is important for PRK recovery.

When the epithelial tissue has sealed, the doctor removes the contact lens at a follow up appointment about 4 to 5 days after the procedure.  When the contact lens is removed, the patient is typically thru the worst part of the recovery after PRK.  Each patient is different but vision improves markedly with the removal of the contact lens and the patient’s vision tends to be rather functional at this point.

In the recovery phase, the patient experiences a gradual improvement in vision day after day.  Patients continue to use medicated drops over this time and have a few more follow up visits so our doctors can monitor the healing of the eyes.  At the follow up visits, the doctor will adjust the dosage of the medicated drop to control the healing of the epithelial tissue and ensure that it heals properly.  Since the epithelial tissue of the cornea regenerates itself every thirty days naturally, it is typically around the 30 day mark after PRK when the patient has achieved the majority of their final visual result.

Pros and Cons of LASIK and PRK

As you have likely gathered so far, the advantages of LASIK over PRK include a significantly faster visual recovery and, comparatively, little-to-no discomfort during the healing phase.  These advantages are directly tied to the LASIK flap that allows the epithelium to be temporarily moved out of the way and replaced, so the patient essentially has their own tissue back as a natural bandage over the treated area.  Most patients have very busy lives and appreciate the ability to able to get back to life much sooner, so LASIK tends to be the more popular procedure of the two.

While LASIK’s advantages are the result of the LASIK flap, PRK’s advantages are the result of not having a flap.  In spite of the longer, more challenging visual recovery after PRK, for certain patients, PRK is the patient’s preference, and in other cases PRK is the better procedure from a medical perspective to treat their vision.

While complications with the LASIK flap are very rare, especially when using modern Bladeless technology, they are eliminated completely with PRK, so some patients choose to have PRK.  For patients such as MMA fighters who accept a high risk of direct trauma to their eyes in their profession or sport, PRK is recommended.  Also because the PRK procedure does not involve a flap, PRK patients tend to have less dry eye after their procedure than LASIK patients.  Most commonly though, patients have PRK instead of LASIK because the PRK procedure requires less corneal tissue thickness than LASIK does, which is of significant consideration for patients with naturally thinner corneas or higher amounts of nearsightedness or both.

Which procedure is best for you?

The most important and first step of getting rid of your glasses and contacts is to visit one of our two Denver area locations for a free consultation to have our LASIK specialist doctors evaluate your eyes to see if you are a candidate for one or both procedures.  You may be a candidate for only one or the other, and if that is the case, our doctors will carefully explain their recommendation.  Most people are candidates to have their vision corrected are actually able to choose which procedure they would prefer, and most people’s choice, including most LVC Surgeons, is LASIK.

So with this overview of LASIK and PRK now in your mind to help your consultation with our doctors, give us a call at 303.202.0669 or contact us thru the web, and we will help find a time for you to come visit us at no cost.  If you are a candidate for vision correction and choose to have your vision corrected with us, whether it is LASIK or PRK, our doctors are so confident in their ability to get you to 20/20 that we will stand behind your results with our exclusive 20/20 or It’s Free Guarantee.