SMILE, Small Incision Lenticule Extraction

SMILE is the acronym for Small Incision Lenticule Extraction, literally "extraction of a lenticule through a small incision." The name describes exactly what is done.

All laser refractive surgery has the same goal: to change the curvature of the cornea, the transparent tissue at the front of the eye that provides most of its optical power. What sets the techniques apart is how they reach the deep layer of the cornea, the stroma, and how they remove tissue from it.

LASIK lifts a flap to expose the stroma, then the excimer laser vaporizes tissue at its surface. TransPRK goes through the epithelium with the laser and sculpts the stroma at the surface, with no flap and no contact. SMILE works differently: nothing is vaporized, nothing is lifted. The femtosecond lasercuts, within the very thickness of the cornea, the two faces of a lens of tissue. This small disc is then removed in a single piece. The volume removed changes the curvature of the cornea, and vision is corrected.

The SMILE sequence, in four steps

1. The lasercuts the back face of the lenticule, deep in the stroma, according to the correction to be treated. The shape and thickness of this disc are calculated from your refraction.

2. The lasercuts the front face of the lenticule, which is more superficial, then a small peripheral incision of 2 to 3 millimeters that will serve as the entry point.

3. The lenticule is detached and removed through this micro-incision, using a fine instrument. This step requires precision, because the lenticule must come out whole.

4. The cornea closes on its own. There are no stitches, no bandage contact lens and no flap to reposition. The epithelium heals along the micro-incision within a few days.

A recent technique, with less long-term data than LASIK

SMILE came into routine practice in themid-2010s, on Zeiss femtosecond lasers. LASIK, on the other hand, has been performed on a large scale since the mid-1990s. To me, this twenty-year gap matters. When you offer someone elective surgery on a healthy eye, the depth of clinical experience is part of the argument.

Understanding how the corneal laser works

SMILE uses only one machine, the Zeiss Visumax 800 femtosecond laser. No excimer laser is involved. The Institut Voltaire is one of the few centers in Paris to have this platform, which went into service in March 2024.

The operating room at the Institut Laser Ophtalmologique Voltaire. On the left, the Zeiss Visumax 800 femtosecond laser, which performs the entire SMILE procedure on its own: it cuts the lenticule inside the cornea, then the micro-incision through which I remove it. On the right, the Schwind Amaris 750S excimer laser, which is not used during SMILE, unlike LASIK and TransPRK.

How a femtosecond laser works

The Visumax 800 works by photodisruption. It emits pulses lasting on the order of a millionth of a billionth of a second, which create microscopic gas bubbles inside the stroma. These bubbles line up with one another and form a cleavage plane in the tissue, with no heat transfer and no mechanical incision.

This is the same technology that cuts the flap in LASIK. The difference lies in the geometry: in LASIK, the laser creates a single plane and a hinge; in SMILE, it creates a closed volume, the lenticule.

What the Visumax 800 brings to SMILE

• A fast cut, about 14 seconds per eye.
• Lower suction pressure compared with earlier generations of femtosecond lasers. The sensation during docking is noticeably more comfortable.
• An even distribution of gas bubbles, which makes separating the lenticule cleaner and removing it simpler. Older femtosecond lasers could leave poorly separated areas, which made the step more difficult.
• No heat transfer to the surrounding corneal tissue.

What SMILE does not use.

The Schwind Amaris 750S excimer laser, which I use for LASIK and TransPRK, offers functions that have no direct equivalent in SMILE. This is a technical point that few websites explain, and it weighs in mypreference for LASIK:

The excimer treats the cornea point by point, based on the complete aberrometry map of your eye measured just before the procedure. Each point of the surface receives the exact ablation that corresponds to it. SMILE, by contrast, sculpts a lenticule whose geometry is calculated from your prescription. The approach is more global, less fine-tuned.

The excimer also benefits from iris recognition and from eye-tracking that follows the eye throughout the treatment, including during involuntary micro-saccades of the gaze. In SMILE, the eye is held still by the interface during the cut, which addresses the issue differently, but centering is determined at the moment of docking.

These differences do not prevent very good results with SMILE on pure myopia. They explain why I consider LASIK more precise as soon as there is astigmatism or a particular aberrometric profile.

Understanding aberrometry and customized treatment

Summary: which laser for which technique

We have SMILE at the Institut Voltaire andI perform it. It is not my preferred technique, and I would rather write that here than let you discover it in consultation.

Three reasons.

The quality of correction. LASIK gives me finer results, especially as soon as astigmatism is involved. Point-by-point excimer treatment, guided bythe aberrometry of your eye, works at a scale that cutting a lenticule does not reach. On pure, moderate myopia, the gap narrows considerably. On somewhat unusual profiles, it widens.

Enhancement options. After LASIK, if a small residual correction remains, I lift the existing flap again and readjust with the excimer laser. The step is simple and well mastered. After SMILE, there is no such flap: the retreatment is done either by surface TransPRK, with the recovery that comes with it, or by creating a flap afterward for LASIK. The choice between the two is made case by case. This weighs in my choice, because a possible enhancement is part of what I must anticipate on the day I decide on the technique.

Clinical experience. LASIK has been performed on a large scale for more than twenty-five years. Its long-term behavior, limits and complications are well known. SMILE is younger. That does not mean it is risky; it means we know less about it.

About the extra cost

SMILE costs €600 more than LASIK. This difference is explained by the cost of using the Visumax 800 per treatment, which is higher than that of a treatment combining the two lasers. I charge it at what it costs me, with no additional margin.

But I owe you my opinion: in most situations, this extra cost does not seem to me justified by the benefit it brings. When the indication is there, combat sports, marked apprehension about the flap, I offer SMILE without hesitation and the extra cost is fully justified. When it isn't, I will tell you that LASIK will serve you better, and that it will cost you less.

About what other surgeons say

Some colleagues see things differently from me and operate mostly with SMILE. They are competent surgeons, and their patients are satisfied. I simply think that, in the way this technique is presented to the public, there is a share of marketing that goes beyond what the data allow us to claim. The word "minimally invasive" has a lot to do with it.

If you consult several surgeons and hear two different views, that is normal. Take the time to meet the surgeons, listen to their arguments, and choose based on how you feel. The machine and the fee matter. Your relationship with your surgeon will matter more.

Here I describe the procedure itself. A separate page covers all the practical details: the appointment notice, the prescription, the anti-anxiety tablet, removing contact lenses, arriving at the clinic, changing into the gown, going home, the first check-up.

Surgery day: preparation and practical details

Before the procedure

You take an anti-anxiety tablet about an hour before. There is no need to fast. When you arrive, after the administrative formalities and the last eye images, you change into a sterile gown and are taken to the pre-op room.

In the operating room, you lie under the Visumax 800. I put in the anesthetic drops. The entire surgery is done under local anesthesia with drops: no general anesthesia, no injection. An eyelid holder keeps the eye open without any effort on your part.

Under the laser

For each eye, the sequence is the same: docking to the interface, cutting the lenticule and the micro-incision, separating then removing the lenticule, rinsing. We then move on to the second eye.

The laser itself works for only about fifteen seconds per eye. The rest of the time is taken up by positioning, the explanations I give you as we go, and the extraction step. Your time in the operating room is very short, about ten minutes for both eyes.

The three stages of surgery day at the Institut Voltaire. On the left, preparation and instillation of the anesthetic drops. In the center, the procedure under the laser. On the right, the recovery room, where you stay until the first sensations settle down.

Right after the procedure

You go to the recovery room for a short rest, until the first sensations settle. I give you UV-protective glasses. After SMILE, there is no need for eye shields at night. My secretaries schedule your first check-up, and I go over the instructions for the first few days again before you leave.

You can go home accompanied, which is what I recommend, or alone by taxi or ride-hailing service. You will not be fit to drive in the hours following the procedure.

Surgery and the check-up

I operate on Friday mornings at the Institut Laser Ophtalmologique Voltaire, 5 rue La Vacquerie in Paris 11th. The first check-up takes place the following Monday afternoon, at my office in Paris 19th (19e arrondissement), rue Archereau. It is a short consultation: checking the cornea, making sure there is no inflammation, measuring the visual acuity achieved. Further check-ups are scheduled at 1 month, then at 3 months or later depending on your situation.

SMILE is a well-established surgery, with a high satisfaction rate. Like any procedure, it carries possible side effects and complications. They remain rare, and you need to know about them to make an informed decision.

Dry eye

This is the most common effect after any corneal refractive surgery. With SMILE, it is generally slightly less pronounced than after LASIK, without a major difference. The 2 to 3 millimeter micro-incision cuts far fewer corneal nerve fibers than the peripheral cut of a flap, so the surface nerve supply is less disrupted.

Dry eye remains possible, especially in the first few weeks. It is treated with preservative-free artificial tears. In the rare more pronounced cases, I have a complete range of treatments: stronger tears, tear gels in the evening, sometimes doxycycline tablets in particular cases, notably dermatological ones.

Prolonged visual haze

Some patients describe slightly milky or less contrasted vision for a few more days than after LASIK. This is related to the interface left by the removal of the lenticule, which takes a little time to become perfectly transparent. It clears up. I mention it because it is the comment I hear most often at check-ups after SMILE.

Halos and night vision

Halos around lights, glare and slightly reduced night vision can appear in the first few weeks, with a peak around the 2nd month. This is temporary and gradually fades in almost all patients. At 6 months and at one year, night vision is generally better than before the procedure.

Difficulties removing the lenticule

This is the complication specific to SMILE. The lenticule must come out whole through an incision a few millimeters long. It can tear, or a fragment can remain in place, which means it has to be found and removed. This makes the procedure longer and can delay visual recovery.

Small tears at the edges of the micro-incision have also been described. They heal with no consequence for the result.

The quality of the cut plays a big role in this risk. The Visumax 800 separates the lenticule much more cleanly than earlier generations of femtosecond lasers, which makes extraction simpler and more reproducible.

An imperfect result and enhancement

Part of the correction may be missing, or the result may not be exactly the one aimed for. After SMILE, an enhancement is less simple than after LASIK. There is no flap to lift again, so the retreatment is done differently: either by surface TransPRK, with its 7 to 10 days of recovery, or by creating a flap afterward to perform LASIK. Both routes work and make it possible to reach the target result; they simply ask more of the patient.

The enhancement is included in the initial fee during the first year. After that, it is offered at a preferential rate up to 5 years after surgery.

Serious complications

Infection, corneal ectasia and lasting loss of visual quality are exceptional events. They occur mainly when pre-operative safety criteria have not been strictly followed. As with any surgery, zero risk does not exist. I carry out a complete assessment beforehand and remain very selective on candidacy criteria, precisely to minimize these risks.

SMILE does not touch the optic nerve, the retina or the internal structures of the eye. It does not cause blindness in the usual sense of the word. Like any surgery, it can in exceptional cases lead to reduced visual quality, a loss of lines of corrected acuity, significant dryness or bothersome light phenomena. These situations remain rare, and the purpose of the pre-operative assessment is to reduce them as much as possible.

Risks and transparency: everything you need to know

SMILE fee: €3,800 for both eyes, i.e. €1,900 per eye. The fee is fixed, whatever the correction to be treated.

That is €600 more than LASIK. This difference comes from the cost of using the Visumax 800 per treatment, which is higher than that of a procedure combining the femtosecond and excimer lasers. My fees are aligned with those of my colleagues at the Institut Voltaire.

What the fee includes

• The procedure, using the Zeiss Visumax 800 laser.
• Clinic fees at the Institut Voltaire.
• Complete post-operative follow-up, with no limit on the number of consultations.
• A possible enhancement during the first year.
• Prescriptions for post-operative medication.

The pre-operative consultation

The pre-operative consultation is charged at the standard rate set by French national health insurance. The arrangements differ depending on the location:

• Offices in Paris 10th (10e arrondissement) and 19th: nothing to pay upfront (direct billing).
• Institut Voltaire (Paris 11th): €50 paid upfront, including a €30 fee supplement (above the standard rate). Your complementary health insurance reimburses at least €20, and often the full amount depending on your plan.

You do not need a referral letter or a prescription from another ophthalmologist to book an appointment.

Payment

Payment is made on surgery day, at the front desk, before the procedure. Accepted methods: bank card, check, bank transfer or direct debit. Payment in 4 installments is possible, by check or direct debit.

Complementary health insurance does not pay the clinic directly. You are the one reimbursed upon presentation of the invoice. If your complementary health insurance covers a significant amount, a payment corresponding to that sum can be deferred and cashed only once you have received your reimbursement. I can send you a quote for your complementary health insurance before the procedure.

Detailed fees, quotes and insurance reimbursements