SMILE Explained: The Newest FDA-Approved Laser Vision Correction

SMILE (Small Incision Lenticule Extraction) represents the newest generation of laser vision correction. FDA-approved in 2016, it combines the flapless advantages of PRK with a fundamentally different laser technique that uses only a femtosecond laser (not the two-laser system LASIK typically requires). For patients who qualify, SMILE offers a distinct recovery and side-effect profile—and some important candidacy limitations to understand.

What SMILE Is and How It Works

The Core Concept: Extract a Lenticule, Not Reshape Layers

LASIK and PRK both reshape the cornea by removing tissue from its surface or surface layer. SMILE takes a different approach: a femtosecond laser creates a precise, lens-shaped piece of tissue—called a lenticule—entirely within the depth of the cornea. The surgeon then makes a small incision (2–4 mm) at the edge of the cornea and removes this lenticule through that incision. As the lenticule is extracted, the cornea physically reshapes itself to fill the void, effectively correcting the refractive error.

Instead of using a laser to ablate (vaporize) tissue, SMILE uses a laser to separate tissue, then mechanically removes it. This distinction matters because it affects nerve disruption, corneal wound strength, and recovery characteristics.

Why the Name: Small Incision Lenticule Extraction

• Small Incision: A 2-4 mm opening, compared to the roughly 20 mm circumferential incision used to create a LASIK flap
• Lenticule: The small disc of corneal tissue removed
• Extraction: The lenticule is extracted through the incision

The procedure is sometimes called "flapless LASIK" in casual conversation, but it is technologically distinct.

The SMILE Procedure Step by Step

Pre-Operative Evaluation

SMILE candidacy assessment is similar to LASIK and PRK screening: corneal topography, thickness measurement, tear-film evaluation, pupil size, retinal examination. However, SMILE has specific prescription limitations (see Candidacy section below) that must be confirmed.

Step 1: Corneal Lenticule Creation

1. The patient is positioned under the femtosecond laser (the same type of laser used to create flaps in bladeless LASIK)
2. Numbing drops are applied
3. A suction ring gently holds the eye in place
4. The laser fires in a precise pattern to create two laser-cut surfaces in the corneal stroma: an outer surface and an inner surface
5. These two surfaces define the shape and volume of the lenticule that will be removed
6. The laser process takes about 20–30 seconds per eye

Step 2: Creating the Access Incision

After the lenticule is defined by the laser, the surgeon creates a small incision (2–4 mm) at the edge (periphery) of the cornea. This incision connects the inner and outer laser-cut surfaces, creating an opening through which the lenticule can be removed.

The small incision size is a defining feature of SMILE—much smaller than a LASIK flap.

Step 3: Lenticule Removal

Using specialized instruments, the surgeon carefully separates the lenticule from surrounding tissue and removes it through the small incision. This step requires precision and manual dexterity, which is why SMILE success is particularly dependent on surgeon training and experience.

Step 4: Incision Healing

Once the lenticule is removed, the incision is closed naturally by the eye's own healing response. Most incisions self-seal without stitches within a few days. Unlike the flap in LASIK (which must be carefully repositioned), the incision requires no realignment.

FDA Approval and Current Status

2016 FDA Approval

The FDA first approved SMILE in September 2016 for spherical myopia only. In October 2018, the approval was expanded to cover myopia with astigmatism and a wider myopia range. The approval was based on U.S. clinical trials involving hundreds of eyes, on top of extensive international experience with the procedure since 2011.

Current Availability

While SMILE is FDA-approved and practiced widely, it is not yet as ubiquitous as LASIK. Not every eye center offers SMILE—it requires the specific laser platform and extensive surgeon training. In major metropolitan areas, SMILE centers are increasingly available, but in smaller regions, LASIK or PRK may be the only options.

SMILE's Candidacy Profile: Important Limitations

What SMILE Can Treat

Myopia (Nearsightedness):

• FDA-approved range: -1.00 to -10.00 diopters
• Some newer data suggests efficacy up to -12.00 diopters, though standard range is -1 to -10
• Most outcomes are excellent within the standard range

Myopic Astigmatism (Combination of nearsightedness and astigmatism):

• Up to 3.00 diopters of astigmatism (when combined with myopia)
• Less commonly up to 5.00 diopters in some reports, though 3.00 is the standard FDA limit

What SMILE Cannot Treat

Hyperopia (Farsightedness): This is the critical limitation. SMILE is not FDA-approved for hyperopia. The laser and surgical technique are optimized for removing tissue (myopia correction), not adding or steepening corneal shape. SMILE is not FDA-approved for hyperopia and no U.S. approval is imminent - farsighted patients should plan on LASIK, PRK, or a lens-based procedure instead.

Presbyopia (Age-related loss of near focus): SMILE cannot restore near-focusing ability. However, monovision correction (optimizing one eye for distance and the other for near) may be an option in selected cases.

Pure Hyperopia or Significant Astigmatism (non-myopic): SMILE does not address these refractive errors.

Optimal Candidacy

The ideal SMILE candidate:

• Has myopia from -1.00 to -10.00 diopters
• Has no significant hyperopia
• Has healthy corneas with adequate thickness (typically 500+ microns)
• Has stable prescription for 12+ months
• Desires faster recovery and minimal dry eye risk
• Has realistic expectations about the small incision and newer technology

Recovery After SMILE

Day 1

• Vision hazy but improving faster than PRK
• Mild discomfort (less than PRK, similar to early LASIK)
• Tearing and light sensitivity present
• No bandage contact lens needed
• Rest recommended

Days 2–3

• Vision clearing noticeably
• Can return to computer work
• Light sensitivity decreasing
• Mild discomfort mostly resolved
• Most patients can drive by day 2–3 with surgeon clearance

Week 1

• Vision clear and functional
• Can resume most activities
• Incision healing well
• Return to exercise with protective eyewear

Weeks 2–4

• Vision continues optimizing
• Halos or glare (if present) improving
• Full return to sports and contact activities
• Dry eye symptoms minimal (one of SMILE's advantages)

Months 1–3

• Vision fully stabilized
• Final refraction measured
• Dry eye rates typically lower than LASIK at this point
• Corneal nerves regenerating

Why SMILE May Be Preferred

Less Disruption to Corneal Nerves

Because SMILE does not create a flap (which cuts many corneal nerves), it disrupts fewer nerve fibers. Post-operative dry eye rates are generally lower with SMILE than with LASIK, and tear production often recovers faster. For patients concerned about dry eye, this is a significant advantage.

No Flap Complications

With no flap, there is no risk of:

• Flap wrinkles
• Incomplete flap creation
• Flap dislocation (rare but possible)
• Epithelial ingrowth under the flap

For patients concerned about flap-related issues, SMILE offers peace of mind.

Smaller Incision

The 2–4 mm incision is much smaller than a LASIK flap (20 mm). This theoretically preserves more corneal structural integrity, though long-term biomechanical studies are still emerging.

Excellent Visual Outcomes

For myopic patients within the approved range, SMILE delivers excellent results:

• roughly 85-90% achieved 20/20 or better in U.S. clinical trials, with many recently published series reporting even higher rates
• 98%+ achieve 20/40 or better
• Patient satisfaction is consistently high in published studies
• Stability is excellent

Limitations and Trade-Offs

Cannot Treat Hyperopia

This is the most important limitation. Anyone with hyperopia (farsightedness) is not a SMILE candidate and must choose LASIK, PRK, or ICL. This excludes a significant portion of the vision-correction population.

No Wavefront-Guided Customization

LASIK can be performed with wavefront analysis, which customizes the laser pattern to each person's unique corneal aberrations. SMILE currently does not offer this level of customization. Standard SMILE uses the person's manifest refraction only.

Cannot Be Enhanced as Easily

If enhancement is needed (to fine-tune the correction), a SMILE enhancement is more complex than a LASIK enhancement. The small incision may need to be reopened, and residual tissue must be carefully managed. Some surgeons perform a LASIK enhancement after SMILE if more correction is needed.

Longer Learning Curve for Surgeons

SMILE requires precise manual extraction of the lenticule, which has a steeper learning curve than LASIK. Surgeon experience matters significantly for outcomes. This is why SMILE results are best from experienced SMILE surgeons.

Fewer Centers Offer It

Unlike LASIK, which is widely available, SMILE is still concentrated in larger metropolitan areas and university medical centers. Finding a qualified SMILE surgeon may require travel.

SMILE vs LASIK vs PRK: Head-to-Head

Who Is an Ideal SMILE Candidate

• Myopic patients (-1.00 to -10.00 diopters)
• Those with myopic astigmatism (up to 3.00 diopters)
• Patients concerned about dry eye risk
• Contact-sport athletes (no flap to dislodge)
• Those valuing smaller incision and corneal nerve preservation
• Patients willing to travel to an experienced SMILE center if needed
• Anyone seeking the newest FDA-approved option with excellent outcomes

When SMILE Is NOT an Option

• Hyperopic patients (farsighted)
• Mixed prescriptions (one eye myopic, one hyperopic)
• Prescriptions outside -1.00 to -10.00 range (very high myopia >-10)
• Patients in regions without SMILE access and unable to travel
• Those needing wavefront-guided customization
• Situations requiring rapid vision recovery (though SMILE is still fast)

FAQs

Is SMILE better than LASIK?

Not universally—it depends on your prescription and priorities. SMILE has advantages in dry-eye risk and corneal nerve preservation, especially for myopic patients. However, LASIK can treat a broader prescription range (including hyperopia), has shorter recovery than PRK, and is more widely available. Both are excellent procedures; the choice depends on individual candidacy and preferences.

Can SMILE correct farsightedness?

No. SMILE is FDA-approved only for myopia (nearsightedness) and myopic astigmatism. It cannot treat hyperopia (farsightedness). If you are farsighted, LASIK, PRK, or ICL are the available options.

How quickly can I see after SMILE?

Most patients see functional vision within 24–48 hours, and clear vision by day 3–4. This is faster than PRK (which takes 5–7 days) but slightly longer than LASIK (where most patients see clearly within 24 hours). Final vision stabilization takes a few weeks.

Does SMILE cause dry eye?

Dry eye rates with SMILE are generally lower than LASIK because fewer corneal nerves are disrupted. Some mild dry eye is common in the first few weeks, but it typically resolves faster than after LASIK. Most patients do not experience long-term dry-eye problems after SMILE.

Can SMILE be retreated if I need more correction?

Yes, but enhancement after SMILE is more complex than LASIK enhancement. The surgeon must carefully manage residual corneal tissue, or a LASIK enhancement may be performed instead. Discuss enhancement options and likelihood during your consultation, as this should factor into your SMILE decision.