What is the smile eye procedure?
Is smile safer than Lasik?
What are the differences between LASIK and SMILE?
Can smile eye surgery correct astigmatism?
The benefits of smile
What is the smile eye procedure?
Small incision lenticule extraction (SMILE), originally called Femtosecond lenticule extraction (FLEx), is a form of laser based refractive eye surgery developed by Carl Zeiss Meditec used to correct myopia, and astigmatism. Although similar to LASIK laser surgery, the intrastromal procedure is novel in that it uses a single femtosecond laser referenced to the corneal surface to cleave a thin lenticule from the corneal stroma for manual extraction. It has been described as a painless procedure. For candidates to qualify for this treatment, they have their corneal stroma thickness checked to make sure that post operative thickness won’t be too thin.
The lenticule to be extracted is accurately cut to the correction prescription required by the patient using a photodisruption laser-tissue interaction. The method of extraction can be via a Lasik type flap, but more recently a flapless technique makes a small tunnel incision in the corneal periphery. Currently in the US the procedure is only approved for nearsightedness.
After the femtosecond laser has separated the lenticule, a blunt spatula is inserted through the incision between the lenticule and the stroma and carefully rotated to ensure that the lenticule is completely detached prior to removal by forceps. The procedure has been described as safe and predictable in treating myopia and astigmatism. Some theoretical advantages are that the technique is minimally invasive compared with other flap based treatments and no collateral damage occurs to surrounding tissue due to the high speed of the femtosecond laser. There are limited studies on corneal wound healing and inflammatory response after this treatment has been carried out. There is a suggestion that the expression of fibronectin which is associated with wound healing is less in this method compared with femtosecond-LASIK. Because SMILE treatment is relatively new compared with other laser correction treatments, result studies are limited, but postoperative five year (SMILE) outcomes indicate that the results have been stable after 5 years of follow-up. In some cases post operative tear secretion and dry eye syndrome have been observed along with similar post operative complications seen in LASIK surgery.
As lenticule extraction techniques evolve, there is a possibility that extracted lenticules can be cryogenically preserved either for future donation, or re-implantation. Proof of concept has been carried out on primates where lenticules were extracted from monkeys and allogenically transplanted into other monkeys with positive results.
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Is smile safer than Lasik?
Both small incision lenticule extraction (SMILE) and LASIK are relatively safe and have similar side effects. SMILE has a lower risk of scarring because it does not involve creating a flap. The remaining possible side effects and complications are similar in both SMILE and LASIK.
The similarities between the two procedures include:
- Both are performed by an ophthalmologist (eye surgeon).
- Both involve using a guided laser.
- Both are performed under local anesthesia.
- Both are performed under 30 minutes.
- Many of the side effects are similar such as blurry vision till the eyes heal, glares, halos, difficulty with seeing in the dark, increased light sensitivity, and dry eyes.
- The recovery time is the same.
- Postoperative care is the same.
The basic eligibility criteria for both the surgeries are the same; they include the following:
- Age over 21 years
- No significant change in vision over the past one year
- Possibility of vision improvement to at least 20/40
- Myopic prescription between −1.00 and −12.00 diopters
- Not pregnant, breastfeeding, or on hormonal therapy at the time of surgery
- Average pupil size about 6 mm in the dark
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What are the differences between LASIK and SMILE?
Main differences between small incision lenticule extraction (SMILE) vs LASIK include:
- LASIK can be used to treat all types of refractive errors, whereas SMILE is used to treat myopia with or without astigmatism. However, SMILE cannot treat isolated astigmatism.
- LASIK involves a flap to be surgically made in the cornea, so the excimer laser reaches the deeper parts of your eye. SMILE is used as a single laser to flatten and reshape the cornea.
- The risk of scarring is higher in LASIK than in SMILE.
- LASIK is not ideal in those with thin corneas. SMILE can be done in those with thin corneas.
- Both the procedures have good patient satisfaction, but the patient satisfaction of SMILE is slightly better.
- Because SMILE is a newer surgery, fewer number of surgeons specialize in SMILE.
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Can smile eye surgery correct astigmatism?
SMILE has been FDA approved for myopia with astigmatism. SMILE is capable of correcting nearsightedness up to -10.00 diopters, and -3.00 diopters of astigmatism.
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The benefits of smile
- Less Invasive Surgery
SMILE is a one step, one laser, minimally invasive procedure. Compared to LASIK or PRK, SMILE is a less invasive laser eye surgery procedure. During LASIK, your doctor creates a flap in order to correct your vision. This flap is 20mm in circumference. During a PRK procedure, an 8mm diameter surface removal is created to correct vision. During a SMILE procedure, your surgeon only needs to create a 3mm key-hole incision in your cornea.
This small incision allows for less disturbance to corneal nerves and more corneal stability post-surgery.
- No Flap Surgery
One of the only drawbacks to a LASIK procedure is the creation of a permanent flap of corneal tissue. During LASIK, a small flap of corneal tissue is created using a femtosecond laser and then folded back. The surgeon then uses a second laser, called an excimer laser, to reshape the underlying corneal tissue and correct vision. Because of this, it is a more complex procedure than its successor, SMILE.
It is important to note that LASIK is an extremely safe and trusted procedure. However, rarely complications can arise. Many of these complications are called ‘flap-related complications’ and are due to the flap created during surgery.
Since no flap is created during a SMILE procedure, there is absolutely no risk for flap-related complications.
- Safe, Accurate, And Fast Visual Recovery
SMILE has been found to be just as safe and accurate as LASIK. SMILE also has the added benefit of a quick visual recovery- It only takes about one to two days to experience the amazing results.
Quiet, Odorless, and Blade-Free
Both LASIK and PRK procedures use a second laser, called an excimer laser, during the procedure. This laser is known to create a loud ‘clicking’ noise when used, which can be disconcerting to some patients. The excimer laser also known to create a noticeable odor during a LASIK procedure, as it is used to ablate corneal cells. Because SMILE does not use an excimer laser, the procedure is both quiet and odorless.
- Reduced Chance of Dry Eye Syndrome
Dry eye is a relatively common side effect of laser eye surgeries. One benefit of SMILE is that it may reduce the chance for dry eye to occur. Because SMILE only involves a small incision made in the cornea, there is potentially a smaller chance of dry eye post-surgery.
- Not a Good LASIK Candidate? SMILE Could be for You
There are three common things that can cause a patient to not be eligible for LASIK:
- Irregularly shaped or thin corneas
- Predisposition to dry-eye or chronic dry eye syndrome
- Patients who perform sports or jobs with a lot of direct contact to the eyes (ex: boxers, fighters, etc)
SMILE can possibly be an appropriate procedure for those who have been disqualified from LASIK candidacy due to these factors.
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