Laser eye surgery has transformed vision correction, offering many the chance to reduce their reliance on glasses or contact lenses. Small Incision Lenticule Extraction (SMILE) is a modern, minimally invasive procedure. It corrects common refractive errors like nearsightedness (myopia) and astigmatism by reshaping the cornea, improving how light focuses on the retina for clearer vision.
How Small Incision Lenticule Extraction Works
The SMILE procedure uses laser technology to reshape the cornea. Initially, the eye is numbed with topical anesthetic eye drops.
A femtosecond laser creates a lens-shaped piece of corneal tissue, called a lenticule, within the cornea. This lenticule’s shape and thickness are calibrated to correct the refractive error. The femtosecond laser also creates a small incision on the corneal surface, typically between 2 to 4 millimeters in length. This incision acts as an access point for the surgeon.
Through this tiny opening, the surgeon extracts the lenticule from within the corneal tissue. Removing this tissue changes the curvature of the cornea. This reshaping corrects the refractive error, improving vision. The small incision then heals naturally, typically within one to two days, without requiring stitches.
Distinguishing SMILE from LASIK
SMILE and LASIK are both laser vision correction procedures, but they differ in their approach to reshaping the cornea. LASIK involves creating a thin, hinged flap on the corneal surface, which is lifted to expose underlying corneal tissue. An excimer laser then reshapes this exposed tissue, and the flap is repositioned.
In contrast, SMILE is a flap-free procedure. The femtosecond laser creates a lenticule inside the intact cornea and extracts it through a small incision, typically less than 4 mm. This keyhole approach means that SMILE disrupts fewer corneal nerves compared to LASIK, potentially lowering the risk of post-operative dry eye. The absence of a flap also reduces the possibility of flap-related complications, such as displacement or wrinkles, which can occur with LASIK.
The smaller incision in SMILE may contribute to better corneal biomechanical stability after the procedure, especially for higher levels of myopia. While LASIK requires a broader corneal flap that can weaken the cornea’s structural integrity, SMILE’s technique preserves more of the anterior stromal lamellae, which are the stronger layers of the cornea. This difference in corneal tissue preservation can be an advantage, particularly for individuals with active lifestyles or those concerned about corneal strength.
Who is a Suitable Candidate for SMILE?
SMILE is primarily designed for correcting myopia and astigmatism. To be considered a suitable candidate, an individual typically needs to be at least 18 years old, and their eyeglass prescription should have been stable for at least 12 months. Stable vision means the prescription has not changed by more than 0.5 diopters per year.
SMILE can correct myopia ranging from -0.50 to -10.00 diopters. For astigmatism, the treatable range is typically up to -3.00 diopters. The combined prescription of myopia and astigmatism should ideally not exceed -10.00 diopters.
Beyond prescription, good overall eye health is important. Candidates should not have underlying eye conditions such as severe dry eye, thin corneas, keratoconus, glaucoma, or advanced cataracts. Certain systemic health conditions, like rheumatoid arthritis or severe diabetes, or being pregnant or nursing, can also temporarily or permanently disqualify an individual. A comprehensive eye examination with a surgeon is necessary to determine eligibility.
What to Expect from the SMILE Procedure and Recovery
Before the SMILE procedure, patients typically undergo a consultation and are given instructions. On the day of the surgery, numbing eye drops are applied for comfort. The procedure is quick, often taking about 5 to 10 minutes per eye, and both eyes are usually treated during the same session. Patients remain awake during the procedure, and a gentle device holds the eye open to keep it still.
Immediately after SMILE, it is common to experience blurry vision, mild discomfort, stinging, or a gritty sensation lasting 6 to 12 hours. The eyes may also be watery or light-sensitive. Patients are advised to rest for the remainder of the day, avoiding activities like reading, watching television, or using a computer. Protective eye shields are often recommended at night to prevent accidental rubbing.
Visual recovery is generally rapid, with many patients reporting improved vision within hours or the next day, often clear enough to drive and return to work. However, vision may fluctuate during the first few weeks as eyes continue to heal and stabilize, with full stabilization taking anywhere from a few weeks to a few months. Common temporary considerations during recovery include mild dry eye, glare, or halos around lights, especially at night. Regular follow-up appointments with the surgeon are important to monitor healing and address concerns.