Though many people who wear glasses or contact lenses would have heard of LASIK eye surgery, the SMILE procedure is probably less familiar. Despite being a relatively new procedure, SMILE laser eye surgery has proven itself to be an excellent alternative to other refractive surgeries for vision correction.
Refractive Surgery for Vision Correction
Refractive eye surgery is a type of procedure designed to address a condition of the eye known as refractive error. Refractive errors refer to a mismatch between the focusing power of the eye and the actual length of the eyeball, leading to blurry vision. It encompasses:
- Short-sightedness (myopia)
- Long-sightedness (hyperopia)
- Astigmatism
Refractive surgery procedures adjust the way that light focuses through the eye so that it can come to a sharp focus on the light-sensitive retina, which is how we perceive clear vision.
Though many people think of refractive surgeries as synonymous with laser vision correction, not all procedures are reliant on the use of a laser.
Procedures such as SMILE surgery, LASIK surgery, and PRK do use a laser, while other non-laser-based procedures include implantable contact lenses and refractive lens exchange.
What is SMILE Eye Surgery?
SMILE surgery stands for small incision lenticule extraction. It is the newest type of refractive surgical procedure, being first used in 2007.
How Does SMILE Surgery Work?
The SMILE procedure utilises a laser tool known as a femtosecond laser. Once your eye has been made comfortable with topical numbing eye drops, your eye surgeon will insert an eyelid holder to help keep your lids open for the duration of your SMILE eye surgery procedure. You will also have a suction ring applied to the cornea for stability.
The computer-guided laser is then applied to your cornea, which is the clear tissue at the front surface of your eye. Without disrupting the layers at the corneal surface, the laser is able to separate a disc of corneal tissue from the deeper layers, which is termed a lenticule. Your eye surgeon can then remove this lenticule from the cornea through a keyhole incision at the edge of the cornea, hence the term “small incision lenticule extraction”. The goal of SMILE eye surgery is to reshape the cornea and correct the way light bends through this surface.
SMILE Laser Eye Surgery: Pros
Minimally invasive
The major benefit of SMILE surgery is that it’s considered minimally invasive. This means that there’s less disruption to corneal tissue compared to other laser eye surgeries, such as the LASIK procedure (laser-assisted in situ keratomileusis) and PRK laser eye surgery.
Low risk of dry eye
By being minimally invasive, the cornea is thought to retain better biomechanical stability after the procedure. And as fewer nerves of the cornea are disturbed, SMILE eye surgery can also be associated with a lower risk of dry eyes post-operatively compared to patients who undergo LASIK.
No flap complications
Compared to LASIK surgery, the SMILE operation also carries a significant benefit as it doesn’t require the formation of a corneal flap. During LASIK eye surgery, a thin corneal flap is cut from the top layers of the tissue to allow another laser tool, an excimer laser, to reshape the cornea layers deeper down. This creates the risk of flap complications, such as dislocation, which are specific to the LASIK operation but avoidable with SMILE.
May be more suitable for thin corneas
As a corneal flap is not necessary with SMILE surgery, which takes up some of the corneal tissue available for reshaping, the procedure may be used for thin corneas that would be unsuitable for LASIK. This also potentially makes it suitable to treat nearsightedness of higher degrees in people with thin corneas.
Fast healing time
Most people notice a significant improvement in their visual acuity within a couple of days, though it can take a few more weeks for vision to stabilise. Compared to LASIK, patients having SMILE tend to be able to return to their usual activities sooner, such as exercise, swimming, and sport.
SMILE Eye Surgery: Cons
Compared to the advantages of SMILE procedures, it comes with relatively few cons.
However, limitations of SMILE include the fact that it can only currently treat myopia and myopic astigmatism. This is unlike LASIK, which is also suitable for hyperopia (long-sightedness).
Being a relatively new procedure, there is less research surrounding SMILE.
It also means that relatively fewer eye surgeons specialize in offering this type of refractive eye surgery.
Another drawback of SMILE is its potentially higher cost compared to LASIK and PRK.
Possible Complications of SMILE
Though overall considered to be a safe procedure, SMILE involves some degree of surgical risk.
Potential complications and side effects include:
- Eye dryness
- Infection
- Light sensitivity
- Pain
- The potential to over- or under- correct refractive errors
- A loss of visual acuity
Am I Eligible for the SMILE Procedure?
Your eye doctor will be the best person to assess your suitability for small incision lenticule extraction. SMILE is associated with excellent patient satisfaction but does come with some limitations, such as which refractive errors it can correct.
Your eye doctor will consider factors such as:
- Your refractive error; patients with constantly changing refractive error are not suitable for refractive procedures until their vision stabilises
- Your eye health; if you have other vision problems or poor eye health that limit your sight, you may be advised against laser vision correction
- Your overall health status; patients with conditions such as poorly controlled diabetes or a low immune system can be at a greater risk of complications
- Your age
If, for whatever reason, you are found to be unsuitable for SMILE, your eye doctor may be able to offer you a different type of operation to correct your vision. For example, since SMILE is available only to treat myopia, if you have hyperopia, you may be considered for PRK or LASIK instead.
Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.
References
SMILE Eye Surgery.
https://www.visioncenter.org/surgery/smile/
Refractive lenticule extraction small incision lenticule extraction: A new refractive surgery paradigm.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5778540/
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