These common eye conditions are called refractive errors. An eye surgeon can correct these refractive errors with laser treatment that reshapes the cornea so that light is properly focused onto the retina. Laser eye surgery is an option for improving vision without glasses or contact lenses.
Over the years and in the course of medical and technical advancements, three types of laser eye surgery have become available: PRK, LASIK and SMILE. For many people with sight issues, these treatments provide vision correction alternatives to wearing glasses or contact lenses. From the three available laser surgeries, ophthalmologists can choose the most suitable procedure for their patients.
SMILE®—short for SMall Incision Lenticule Extraction—uses technology known as a femtosecond laser system with high precision and speed to reshape the cornea. The laser creates a small, disc-shaped piece of corneal tissue, called a lenticule, inside the cornea. This process takes an average of 30 seconds. The surgeon then removes the lenticule through a small incision at the front part of the eye. This reshapes the cornea and corrects the refractive error.
SMILE is the most recently developed method of laser eye surgery. This advanced procedure provides eye surgeons and their patients with a minimally invasive option for correction of some vision defects.
Single-step procedure: SMILE is performed with a short-pulse, fast-repetition femtosecond laser system. The laser creates a thin layer just beneath the surface of the eye, and at the same time creates a tiny opening on the surface of the eye. The laser works silently, and the patient remains in one place throughout the procedure.
All-femto: SMILE uses a femtosecond laser, programmed to pass harmlessly through the upper layers of the cornea, focusing only at a specific sublayer of the cornea to create the lenticule. This provides the following advantages:
- No removal of the outer layer of the cornea
- Only a very small incision on the surface of the eye
Talk to your eye doctor about laser eye surgery as well as other solutions based on your individual needs. Your doctor will decide if you are a good candidate for SMILE after completing several diagnostic tests.
Preparing for surgery
Before and on the day of surgery, patients are usually directed by their doctor to prepare as follows:
- 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.
- Wear no makeup, perfume or lotion the day before the procedure. These products may leave debris around the eye and eyelashes, which increases the chance of infection.
- Arrange for someone to drive you home after surgery. You may also need alternative transportation for the next few days.
Numbing the eye
To reduce pain during the surgery, anesthesia drops are given to numb the eye. An eyelid holder is used to prevent your eye from blinking during surgery.
Creating the lenticule and the incision
After the eye is numb, a contact glass is placed gently on the eye and connected to the laser device. You may feel slight pressure when this occurs. Once the eye is stationary, the laser creates a disc-shaped lenticule within the stroma, an inner sublayer of the cornea. At the same time, the laser creates a small access incision on the corneal surface less than 6 mm wide.
Removing the lenticule
The surgeon removes the lenticule through the small, laser-generated incision.
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, it is recommended that you not rub the operated eye, and to rest and not overexert yourself. Your doctor may also recommend wearing a shield over the eye for one week while sleeping to avoid accidentally scratching the eye before it heals. Doctors typically schedule a follow-up exam the day after surgery and after one month.
SMILE is a minimally invasive procedure, which means discomfort is usually minimal during the healing period. In most cases, vision stabilizes within one week following the operation. After SMILE, patients are normally able to drive, work, wear makeup and participate in sports and other activities just a few days following treatment.
Who is eligible for SMILE?
As with all other laser vision correction methods, you will have to undergo a detailed eye examination to find out if SMILE is suitable for you. The nature and degree of the refractive error, and the curvature and thickness of the cornea, play a role in your doctor determining if SMILE is an option for you. Your profession, lifestyle and hobbies are also important considerations. If you often participate in contact sports, your doctor might recommend SMILE over alternative laser vision correction treatments.
How is SMILE different from PRK and LASIK?
Step 1: Lenticule creation
A thin lenticule and small incision are created inside the intact cornea.
Step 2: Lenticule removal
The lenticule is removed through the incision with minimal disruption to the corneal biomechanics.
Step 3: Impairment is corrected
Removing the lenticule changes the shape of the cornea, thereby achieving a refraction correction.
Step 1: Flap creation
The eye is anesthetized with special drops. Femtosecond laser pulses are used to create a flap on the surface of the cornea.
Step 2: Convenient interplay
With setups that have a pivoting patient supporting system, the patient is conveniently moved from the femtosecond laser to the excimer laser.
Step 3: Flap is folded back
The prepared flap is folded back like the page of a book, exposing the inner corneal tissue to be treated.
Step 4: Corneal sculpting
The excimer laser removes the corneal tissue point by point within a few seconds, thereby correcting the visual defect.
Step 5: Flap is repositioned
Then, the flap is returned to its original position, protecting the eye much like a natural bandage.
Step 1: Layer removal
The epithelial layer of the cornea is removed.
Step 2: Corneal sculpting
An excimer laser sculpts the corneal tissue within a matter of seconds to correct the refractive error.
Step 3: Eye protection
Finally, a protective bandage lens is placed over the eye until the epithelium heals within a few days.
After SMILE, how long does it take before I can see properly without glasses or contact lenses and return to my normal routine?
The healing process can differ for every patient. In most cases, visual acuity is very good one or two days after the procedure and stabilizes within one week. After SMILE, the majority of patients can drive, work and participate in sports and other activities without glasses or contact lenses just a few days following treatment.
My eye doctor has never heard of SMILE. Is this not a popular procedure?
SMILE, the latest advancement in laser vision correction, was approved by the U.S. FDA in 2016. While there is high awareness about SMILE worldwide, more and more U.S. ophthalmologists are discovering the procedure. Worldwide, over 2,000 surgeons have already successfully treated more than 2.0 million eyes with SMILE.
Is SMILE a proven procedure?
Femtosecond laser technology is clinically proven and has been used for LASIK as well as in cataract surgeries. SMILE is the latest procedure developed using this laser technology. It has been performed in controlled clinical studies since 2007 and has been commercially available outside of the U.S. since 2011. The procedure is now well-established in over 70 countries worldwide.