PRK – the very first laser vision correction method. ReLEx SMILE – one of the most recent methods to have entered into the playing field in the last few years. How do these well-known procedures compare? Read on to find out!
Intro
PRK
PRK (PhotoRefractive Keratectomy) is an Advanced Surface Ablation (ASA) procedure, meaning that there is no cutting to create a flap to allow the laser to access and reshape the cornea. Instead the outermost layer of cells is gently scraped away manually after being dissolved.
It came into existence in the early 1990s and was the very first laser vision correction method introduced into the world. Throughout the decades, we have seen various iterations of PRK, ultimately leading to what we have today with TransPRK.
ReLEx SMILE
ReLEx SMILE (Refractive Lenticule Extraction, Small Incision Lenticule Extraction) was created with the aim of bringing over some of the benefits of LASIK, while being minimally invasive. It makes use of the creation and removal of a tiny lens-shaped piece of corneal tissue within the eye, to reshape the cornea.
ReLEx SMILE was introduced to the world in 2011 by ZEISS, and in 2016, it was introduced into the US after passing the US Food and Drug Administration’s (FDA) notoriously strict regulations and safety standards.
Treatable Conditions
PRK
- Hyperopia (difficulty seeing objects up close)
- Myopia (difficulty seeing objects at long distances)
- Presbyopia (difficulty focusing on objects up close, in older age a.k.a. lao hua yan)
- Astigmatism (distorted, blurry vision at any distance)
ReLEx SMILE
- Myopia (difficulty seeing objects at long distances)
- Astigmatism (distorted, blurry vision at any distance)
Procedure Steps


Pros
PRK
- Flapless
- Low impact on corneal stability
- No flap complications
- Suitable for thinner corneas
ReLEx SMILE
- Flapless
- Low impact on corneal stability
- No flap complications
- Low incidence of dry eyes
- Low risk of affecting night vision
- Almost no pain
- Fast recovery
Cons
PRK
- Risk of dry eyes
- Risk of affecting night vision
- Discomfort during healing
- Slow visual recovery
- Risk of hazy vision
ReLEx SMILE
- 1% risk of lenticule complications (suction loss, unsuccessful extraction, lenticule tear), requiring the patient to switch to TransPRK
- More narrow range of suitability criteria (hyperopia; high myopia or thin corneas not eligible)
- ReLEx SMILE cannot be performed twice, meaning that any further enhancements will have to be done using a different laser vision correction method
Conclusion
We hope that this comparison gives you a good idea of the advantages and disadvantages of both procedures. If you want to learn more about other laser vision correction methods, please visit our comparison table, or check out the comprehensive article comparing two of our main procedures at Clearvision Singapore – TransPRK and ReLEx SMILE.
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