SMILE: A brief guide

Minimally invasive laser eye surgery for vision correction

If you’re considering laser surgery to correct a refractive error such as nearsightedness and/or astigmatism, SMILE may be a viable option. Here’s what you need to know about this high precision solution.

What is SMILE?

Minimally invasive surgery for correcting vision

Small Incision Lenticule Extraction with SMILE is the most recently developed type of laser eye surgery. It’s a minimally invasive procedure that can correct various vision impairments such as nearsightedness and astigmatism.

It’s a popular option, with over 900 clinics and 1800 practicing surgeons worldwide who use SMILE. By June 2020, myopia and/or astigmatism were corrected with SMILE in more than 3.0 million eyes in over 70 countries.

How does SMILE work?

SMILE is running on a femtosecond laser to reshape the cornea. This femtosecond laser is an extremely short-pulsed, near infrared laser often also used to create a LASIK flap. The laser's high peak intensity over a very short pulse duration (within a few femtoseconds of time) allows it to create micro-precision single holes (bubbles) that forms together cuts or planes in the corneal tissue without affecting the surrounding tissue.

It takes an average of 23 seconds for the laser to create a small lens-shaped piece of corneal tissue (called the lenticule) inside the cornea. The surgeon then removes the lenticule through a small incision outer part of the eye. This reshapes the cornea and corrects the refractive error.

The femtosecond laser produces a thin layer just beneath the surface of the eye, and at the same time creates a small opening. It’s an almost silent, noiseless, odourless procedure and the patient can remain in the same position from start to finish.

Benefits

Femtosecond lasers are designed to harmlessly pass through the upper layers of the cornea, to create the lenticule only at a specific sublayer inside the cornea, which means:

  • With an incision smaller than 4mm on the eye surface, SMILE supports a minimally invasive procedure .
  • The outer layer of the cornea doesn’t have to be removed.
  • Corneal nerves stimulating the tear glands are less affected and are still able to help keep the eye lubricated. Side effects, such as dry eye syndrome, are rare after SMILE.
  • Maintaining the corneal stability is supported, because the entire upper layers of the cornea are virtually unaffected.

Preparing for Surgery

Before and on the day of surgery

Before the surgery patients are usually directed by their doctor to:
 
  • Stop wearing hard contact lenses for at least four weeks and soft lenses for two weeks before surgery, because they may interfere with preoperative diagnostic tests.
  • Don’t make-up, perfume or lotion the day before and on the day of the procedure. These products may leave debris around the eye and eyelashes, which increases the chance of infection.
  • Arrange for alternative transportation directly after the surgery and possibly for the next few days following surgery.

The steps

Numbing the eye

Numbing the eye

To reduce pain during the surgery, anaesthesia drops are given to numb the eye. An eyelid holder is used to prevent the eye from blinking during surgery.

Creating the lenticule and the incision

Creating the lenticule and the incision

After the eye is numbed, it needs to be immobilized for the surgery. This is done with a contact glass, which is placed gently on the eye and connected to the laser device. You may feel slight pressure during this step. Once the eye is held stationary, the laser creates a lenticule within the stroma (an inner sub-layer of the cornea) and creates an access incision on the corneal surface that is less than 4mm wide.

Removing the lenticule

Removing the lenticule

The surgeon removes the lenticule through the small laser-generated incision.

Correcting the refractive error

Correcting the refractive error

Removing the lenticule changes the shape of the cornea, correcting the refractive error. The incision is so small that it will seal itself after some time.

After surgery

After surgery, it is recommended
 
  1. not to rub the operated eye, to rest and not to overexert yourself. 
  2. Your doctor may recommend wearing a patch for one week while sleeping to avoid accidentally scratching the eye.
  3. Since SMILE supports a minimally invasive application, the discomfort felt during the healing process is minor as well. 
  4. Within a few days after the treatment, patients are normally able to drive, work, wear make-up and participate in sports.

Potential side effects

Even though the surgical risk is minimized with SMILE, no surgical intervention is free of risks and side effects. Your physician can explain all potential risks to you and decide whether you are eligible for surgery.
 
Potential side effect may include:
 
  • Disorders of the cornea, retina and other parts of the eye
  • Visual disturbance
  • Visual impairment 
  • Ocular pain

You may also experience some temporary limitations such as delayed visual recovery.

Also bear in mind that over- or undercorrection can occur after any laser vision surgery. Not everyone achieves a spot-on refractive outcome after the operation. The amount of vision correction can vary depending on individual conditions and a residual refractive error can remain, which may cause patients to still need glasses or contacts after surgery.
However, if you are significantly undercorrected, your physician may recommend that you undergo a retreatment. To treat overcorrection, eye drops or soft contact lenses may be prescribed.
Further possible complications and side effects after the lenticule extraction and alternative types of laser vision correction are explained under potential risks.

Frequently Asked Questions

Who is eligible for SMILE?

SMILE is designed to correct myopia, astigmatism or a combination of the two, but is currently not an option for farsightedness (hyperopia) yet.

The nature and degree of the refractive error, and the curvature and thickness of the cornea also play a role.

Your profession and hobbies are also important. If you often participate in strenuous contact sports, your doctor might recommend a treatment with SMILE.

As with other laser vision correction methods, you will first need to undergo a detailed eye examination to determine whether you are a suitable candidate.
Together, you and your doctor can chose the best option to suit your needs.

PRK/LASEK also requires no flap in the cornea. How do these solutions differ from SMILE?

PRK/LASEK procedures have a longer healing time and involve some discomfort until reaching the final stabilized vision result. The stabilization of visual acuity also takes more time.

After SMILE, how long does it take before I will be able to see properly without glasses or contact lenses and return to my normal routine?

The healing process differs for every patient. In most cases visual acuity is very good one or two days after surgery and stabilizes within one week. Just a few days following the treatment, the majority of patients are able to drive, work, and participate in sports without glasses or contact lenses.

My eye doctor has never heard of SMILE. Is this not a popular solution?

Lenticule Extraction is the latest advancement of laser vision correction and SMILE has been available since 2011. The technique is known and recognized by medical trade associations related to refractive laser eye surgeries.

The popularity of SMILE continues to grow, and over 1,800 surgeons have already successfully treated more than 3 million eyes.

Is SMILE a proven application?

Femtosecond laser technology is clinically proven and is used for Femto-LASIK as well as cataract surgery. SMILE is the latest development using this laser technology for laser vision correction.

It has been performed in controlled clinical studies since 2007 and has been commercially available since 2011. The first SMILE-patients have been monitored for over ten years post-treatment. It is currently established in over 70 countries worldwide.

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