Laser Vision Correction

The devil is in the details; How PRK differs from LASIK

By January 30, 2020 No Comments

Author: Dr Val Phua MBBS, MMed (Ophth), FRCOphth, FAMS
Photo by: Soroush Karimi

PRK (Photorefractive keratectomy) and LASIK (Laser-Assisted In Situ Keratomileusis) are 2 very popular choices for laser vision correction. They are indeed “same same but different” and here is an overview to help shed some light on these 2 procedures.

PRK is a safe and effective alternative to LASIK, however the recovery process is slightly more prolonged with some discomfort.

As with the LASIK procedure, the eye is numbed with eye drops to ensure comfort during the procedure. The thin layer of “skin” of the cornea is removed by different means, be it a gentle scraping, applying some alcohol or even the use of a laser. A corrective excimer laser is then applied to the surface of the cornea to reshape it and allow the eye to focus better. A bandage contact lens is then applied to help the eye heal.

The procedure itself is painless but once the numbing eye drops wear off, patients do experience discomfort, glare and halos in the early recovery phase. This feeling of discomfort takes about 5-7 days and vision slowly stabilises over 3 months. During this period, eye drops are given to prevent infection and minimise scarring and also to keep the eye comfortable.

The results from PRK is comparable with LASIK in terms of best corrected vision and it has the benefit of not having a LASIK flap, however the healing process may vary in each individual resulting in some needing some enhancement with the passage of time.

LASIK is a highly dependable, time-tested means of reshaping the cornea to help the eye focus images onto the retina. The procedure itself has 2 main steps.

The first step is creating a thin LASIK flap. This is done after numbing eye drops are given to make the process painless. Traditionally, a fine blade (microkeratome) was used for this step, however with advances in femto-second laser technology, flap creation with the microkeratome has largely been superceded by the femto-second laser. The flap is then lifted and the eye prepared for the application of corrective laser.

Next, a corrective excimer laser is applied to reshape the cornea and allow the eye to focus better. This step is painless and typically takes seconds depending on the degree of correction needed. The flap is then replaced and a bandage contact lens applied.

Most patients who undergo LASIK will notice an improvement almost immediately and some with tight busy schedules can even return to work the next day. The recovery process for LASIK is quite different from advanced surface ablation with minimal discomfort and much faster stabilization of vision after the laser procedure. More than 98% of patients are satisfied with their vision after LASIK.

Which procedure should you go for? In addition to understanding the above, further assessments by taking a thorough history, eye examination and specialised tests are needed before coming to a conclusion on which procedure would best help meet your vision goals, so the short answer is: more tests needs to be done before you know for certain. Just as a primer, candidates who have slightly thinner corneas and are actively involved with contact sports may want to consider PRK. Candidates who have slightly thicker corneas and not participating in contact sports may want to consider LASIK to enjoy the quick recovery time expected from it.