SMILE Pro Enhancement: Why Touch-Ups Are More Complicated Than LASIK

When patients consider laser vision correction, the conversation usually centers on the procedure itself. What does it feel like? How fast is recovery? How sharp will my vision be?

A question that comes up less frequently in those early consultations: what happens if I need a touch-up later?

It is the right question to ask. No refractive procedure achieves a perfect refractive outcome 100% of the time. A small percentage of patients end up with mild residual myopia, astigmatism, or hyperopia after surgery. For those patients, a second procedure (called an enhancement or touch-up) refines the result.

For LASIK, enhancement is one of the most predictable, well-studied procedures in modern ophthalmology. For SMILE Pro, enhancement is genuinely complicated, and in the United States it is structurally more limited than what surgeons can offer in Europe or Asia.

Here is what every prospective SMILE Pro patient should understand before surgery.

The Short Answer

LASIK enhancement is a single, standard procedure that has been refined for over two decades. The original flap is gently lifted, the excimer laser fine-tunes the correction, and the flap is replaced. The same technology that performed your original LASIK performs your enhancement. It treats myopia, hyperopia, or astigmatism. Recovery is fast. Outcomes are predictable.

SMILE Pro enhancement is a category, not a single procedure. There are four distinct pathways, each with meaningful drawbacks, and the pathway most surgeons consider technically optimal (cap-to-flap conversion using Zeiss CIRCLE software) is not approved or commercially available in the United States. American SMILE Pro patients who need an enhancement face a more constrained menu of options than international patients have access to.

This is not a marketing claim. It is documented in peer-reviewed refractive surgery literature, presented at the American Academy of Ophthalmology, and openly discussed by the surgeons who perform these procedures.

How Often Are Enhancements Actually Needed?

Per recent data presented at the AAO October 2025 Refractive Surgery Subspecialty Day by Dr. Nandini Venkateswaran of Massachusetts Eye and Ear and Harvard Medical School, enhancement rates after SMILE are under 4%. Risk factors for higher enhancement rates include older age and higher preoperative manifest refraction. Most enhancements happen in the first year, typically for undercorrection.

Modern LASIK enhancement rates are dramatically lower than older figures suggested. Single-center academic data from Massachusetts Eye and Ear (Harvard Medical School) over 14 consecutive years through 2023 show LASIK enhancement rates around 1.45%, performed on the same WaveLight EX500 excimer laser platform used at Feinerman Vision. A 2023 study in the Indian Journal of Ophthalmology (Mathur et al.) directly compared 6,350 SMILE eyes to 8,176 LASIK eyes and reported nearly identical enhancement rates: 0.5% for SMILE versus 0.44% for LASIK.

In other words, the older “7% to 20%” historical LASIK enhancement rate range reflects 1990s and 2000s technology with mechanical microkeratomes and earlier-generation excimer lasers. Modern femtosecond-flap LASIK with wavefront-guided or wavefront-optimized ablation produces enhancement rates that are essentially equivalent to SMILE, and in some published series, lower than SMILE.

The marketing argument that “SMILE has a lower enhancement rate than LASIK” was technically true a decade ago but is no longer supported by recent peer-reviewed data. Both modern procedures land in roughly the same 1% to 5% range across published series. The clinically meaningful question is not which procedure has a lower enhancement rate, it is what happens when an enhancement is needed.

This article is about what actually happens in those cases when an enhancement is needed.

The Four SMILE Pro Enhancement Pathways

When a SMILE Pro patient needs an enhancement, the surgeon must choose from four distinct techniques. Each has trade-offs.

Option 1: PRK as a SMILE Pro Enhancement

This is the most common SMILE Pro enhancement approach in the United States. The surgeon removes the corneal epithelium with an alcohol or brush technique, then applies the excimer laser at the corneal surface. Mitomycin C is mandatory for at least 30 seconds during the procedure to prevent corneal haze, which is a significantly higher risk after PRK over a previous SMILE cap than after primary (first-time) PRK.

Pros:

• No new flap or cap interface created
• Preserves more corneal biomechanical strength than flap-based options
• Familiar technique for most refractive surgeons
• Outcomes are reasonably predictable

Cons:

• Recovery is slow and uncomfortable. Patients describe days of pain and weeks of visual fluctuation, compared to hours for a LASIK flap-lift enhancement.
• Approximately 2.5% risk of postoperative corneal haze, even with mitomycin C
• Patients describe the experience as going from a comfortable modern procedure to a painful older one
• Vision may take 1 to 3 months to stabilize after PRK enhancement, versus days after a LASIK flap-lift

Option 2: Thin-Flap LASIK Above the SMILE Plane

Here the surgeon creates a brand new LASIK flap (typically 90 to 100 µm thick) in the thin layer of cornea above the original SMILE lenticule cut. The excimer laser then ablates within the small remaining tissue.

The US-specific problem: Per FDA approval, SMILE Pro caps in the United States are locked at 120 µm. International surgeons typically use 135 to 145 µm caps, which leaves more room for a safe thin-flap enhancement. A US patient with a 120 µm cap and a 100 µm thin-flap LASIK enhancement leaves only 20 µm of stromal tissue between the two cut planes.

Why this matters: femtosecond laser tolerance compounds across two procedures.

A femtosecond laser does not cut at exactly the programmed depth every time. Even with the most accurate platforms, peer-reviewed studies document that flap and cap thickness can deviate from intention by a meaningful margin. Per Reinstein and colleagues in the Journal of Refractive Surgery, VisuMax cap thickness has a documented range from −11 µm to +14 µm relative to intended thickness. Other published femtosecond platforms have shown standard deviations of 13.8 to 15.5 µm for flap creation. The bottom line: real-world femtosecond laser cuts can be off by more than 15 µm in either direction, and excimer lasers are significantly more accurate than femtosecond lasers for tissue ablation.

Now consider what happens when these tolerances stack across two procedures:

• Original SMILE Pro: Intended 120 µm cap. Worst case, the laser cut at 105 µm (15 µm thinner than intended).
• Enhancement thin-flap LASIK: Intended 100 µm flap. Worst case, the laser cut at 115 µm (15 µm thicker than intended).

In that plausible scenario, the enhancement flap is now cutting deeper than the original SMILE cap. The two cut planes overlap or cross, and the enhancement laser is no longer in fresh stromal tissue, it is intersecting the original SMILE plane. The clinical consequences include:

• Buttonhole flap creation: the new flap perforates into the SMILE interface and cannot be lifted as a clean flap
• Tissue slivers: small fragments of stroma separate from the cornea between the two cut planes
• Gas bubble breakthrough: during femtosecond laser flap creation, gas escapes through the original SMILE plane, causing irregular flap edges
• Tissue bridge perforation: the residual stromal bridge between the two cut planes ruptures

Each of these can cause permanent visual symptoms, irregular astigmatism, or in severe cases, loss of best-corrected visual acuity. The risk is meaningfully higher in the United States than in international markets specifically because of the 120 µm cap thickness lock combined with normal femtosecond laser tolerance.

Pros:

• Faster recovery than PRK
• Familiar procedure mechanics for surgeons trained in LASIK

Cons:

• Compounded femtosecond laser tolerance can eliminate the safety margin entirely or invert it
• Buttonhole flap creation risk
• Tissue bridge perforation risk
• Gas bubble breakthrough during cutting
• Tissue sliver formation
• Margin for surgical error is small to none in plausible anatomical scenarios

This is why several experienced US refractive surgeons consider thin-flap LASIK enhancement of SMILE Pro genuinely dangerous in routine practice, even with skilled surgeons and careful pre-operative pachymetry. The mechanics simply do not leave enough room for normal femtosecond laser tolerance.

Option 3: Thick-Flap LASIK Below the SMILE Plane

Here the surgeon creates a deeper LASIK flap (typically 140 to 160 µm) that intentionally incorporates the original SMILE lenticule plane within the new flap.

Pros:

• Avoids the tight tissue margin problem of thin-flap LASIK
• Allows full ablation depth within the new flap

Cons:

• Requires more residual stromal bed thickness than the patient may have available
• Cutting deeper into the stroma reduces residual stromal bed thickness and compounds the biomechanical weakening already introduced by the original SMILE Pro procedure
• Increases the risk of post-enhancement corneal ectasia
• Not appropriate for patients whose corneas are within the normal range but on the thinner side

A 2019 Journal of Refractive Surgery porcine eye biomechanical study found that LASIK enhancement of a SMILE cornea induced approximately 7% additional biomechanical weakening, while PRK and Re-SMILE enhancements did not. Corneal cross-linking can partially compensate (~20% increase in elastic modulus), but it is an additional procedure with additional risks, high cost and recovery time.

Option 4: Cap-to-Flap Conversion (CIRCLE Software)

This is the enhancement technique Zeiss officially designed for SMILE patients. CIRCLE software, built into the VisuMax laser platform, converts the original SMILE cap into a LASIK-style flap by creating a peripheral lamellar ring and a vertical junction cut. The result, in the words of multiple refractive surgeons, is that “at the end of surgery, it is as if the patient never had SMILE and only had LASIK.” The flap can then be lifted, the excimer laser applied, and the flap replaced, just like a standard LASIK enhancement.

Pros:

• Visual recovery is rapid
• Outcomes are highly predictable
• Considered by many SMILE surgeons to be the most elegant enhancement technique

Cons:

• Not approved or commercially available in the United States (see below)
• The converted flap is typically thicker than the original SMILE cap (often 130 to 160 µm vs. 120 µm), which removes additional load-bearing stromal tissue. For patients whose corneas are within the normal range but on the thinner side, this can drop the residual stromal bed below safe thresholds and increase the risk of post-enhancement corneal ectasia.
• Requires careful pre-operative pachymetry to ensure adequate residual stromal bed thickness. If thickness is insufficient, the surgeon must consider PRK instead or advise the patient against enhancement.

The fundamental problem: CIRCLE software is not approved or commercially available in the United States. It is available in Europe, Asia, and other markets. Per the EyeWiki keratorefractive lenticule extraction surgery article, “This technique is not approved for use in the United States but is utilized in other regions.”

This is a significant limitation that prospective US SMILE Pro patients are rarely told about during pre-operative consultations.

The Off-Label US Workaround: “Pseudo-Circle”

Some US surgeons have adopted an off-label workaround called the cap-to-flap or “pseudo-Circle” technique. The procedure works like this:

1. The surgeon programs the VisuMax laser to create a LASIK flap
2. Suction is established on the eye
3. Suction is intentionally broken partway through the cut
4. Suction is re-established and the laser completes only the vertical side cut
5. The cap is converted into a flap that can be lifted

In peer-reviewed literature, this is described variously as “pseudo-Circle,” “tricking the laser,” or “off-label flap conversion.” A formal CRSToday editorial note states: “Any form of surgical enhancement of a primary laser vision correction procedure is off label.” This is true for all four SMILE Pro enhancement pathways in the United States.

In experienced hands, the pseudo-Circle technique can produce outcomes comparable to true CIRCLE conversion. But it carries additional risks not present with the CIRCLE software, which is only available internationally:

• Tissue slivers can form at the cap-flap interface
• The absence of a vertical junction cut may produce slightly incongruous tissue planes
• There is no manufacturer-validated protocol or formal surgeon training pathway specific to this technique

For prospective patients, the question is not whether pseudo-Circle works in skilled hands. It does. The question is whether you want to begin a refractive surgery journey knowing that if you need an enhancement, the best available technique is one that is performed by “tricking the laser” by intentionally interrupting laser suction.

The Hyperopia Trap

This is the SMILE Pro enhancement issue that gets the least attention but is potentially the most consequential.

SMILE Pro is FDA approved only for the treatment of myopia and myopic astigmatism. It is not approved for hyperopia. If a SMILE Pro patient ends up overcorrected after surgery (i.e., they wanted to correct nearsightedness and ended up slightly farsighted), the SMILE Pro laser cannot treat them at all.

Their enhancement options narrow to:

• PRK on top of the cap. But here is a critical fact most patients do not know: PRK for hyperopia produces meaningfully worse outcomes than PRK for myopia. Per a systematic review and meta-analysis in the Journal of Optometry (Hashemi et al.), hyperopic PRK has a 32.5% incidence of postoperative corneal haze, which is significantly higher than myopic PRK. The authors attribute the difference to the unique biology of peripheral corneal keratocytes, which are removed during hyperopic ablation but preserved during myopic ablation. Hyperopic PRK also shows higher regression rates, more unstable visual outcomes, and less predictability than myopic PRK, particularly in moderate to high hyperopia.
• Off-label flap-conversion enhancement, performed on a cornea that has already undergone surgery, with all of the femtosecond laser tolerance issues and other risks described above.

A LASIK patient in the same situation is treated with a standard hyperopic LASIK enhancement on the WaveLight EX500 platform. The EX500 is FDA-approved for the treatment of hyperopia, while SMILE Pro is not. The enhancement is the same procedure as the original LASIK, or even easier if the surgeon simply re-lifts the previous LASIK flap.

This is not a hypothetical. SMILE procedures have a documented tendency toward myopic overcorrection in some patients, particularly higher prescriptions. A patient who chose SMILE Pro specifically to avoid LASIK and ended up needing flap-based or PRK-based hyperopic enhancement is in a genuinely difficult clinical position with no good options.

What LASIK Enhancement Actually Looks Like

For contrast, here is what happens when a LASIK patient needs an enhancement at Feinerman Vision:

1. The patient comes in for a routine post-op visit and we determine that the residual refractive error meets enhancement criteria
2. We schedule the enhancement procedure, typically 3 to 6 months after the original LASIK to allow full stabilization
3. On the day of enhancement, the original corneal flap is gently lifted using a standard flap-lift technique. This takes seconds and uses no femtosecond laser.
4. The WaveLight EX500 excimer laser is programmed with the recalculated treatment profile
5. The ablation is performed on the existing stromal bed, usually in under 15 seconds.
6. The flap is replaced
7. The patient leaves with vision already noticeably sharper than when they walked in

Total procedure time: under 10 minutes. Recovery: hours to days, similar to the original LASIK. Treats myopia, hyperopia, or astigmatism without restriction. No workarounds required.

Many LASIK enhancement patients describe the experience as anticlimactic compared to their original LASIK, which is exactly the point.

The Lifetime Enhancement Coverage Difference

At Feinerman Vision, all primary LASIK procedures (both Wavefront-Optimized LASIK and WaveLight® Plus LASIK) include lifetime enhancement coverage. If your eyes change over time and you need a touch-up years or decades after your original procedure, the enhancement is provided at no additional cost as long as you have remained under our care.

Lifetime enhancement coverage is meaningful only if the enhancement procedure itself is straightforward. With LASIK, lifetime coverage means lifetime peace of mind. With SMILE Pro, even when other practices offer lifetime coverage, the enhancement is structurally more complex and less predictable, and the CIRCLE software is not available to US surgeons.

Why Most Orange County Refractive Practices Do Not Routinely Offer SMILE Pro

Step back from the clinical specifics for a moment. The structural enhancement limitations of SMILE Pro are part of why many Orange County refractive practices have not adopted SMILE Pro at scale, despite the availability of the Zeiss VisuMax 800 platform.

I do not perform SMILE Pro at Feinerman Vision. I have evaluated it carefully against WaveLight® Plus LASIK, and in my clinical judgment the combination of WaveLight® Plus’s superior visual outcomes and LASIK’s simpler, more predictable enhancement pathway makes WaveLight® Plus LASIK the stronger choice for the vast majority of refractive candidates. That judgment now rests on two independent randomized contralateral eye trials: the Kanellopoulos head-to-head against SMILE Pro presented at the American Academy of Ophthalmology in October 2025 (98% versus 82% achieving 20/12.5 or better at three months), and the Khoramnia trial published in Ophthalmology (2025;132(10):1169-1179) showing that WaveLight® Plus ray-tracing, planned entirely from objective measurements without a manifest refraction, matched or exceeded wavefront-optimized LASIK on refractive accuracy.

There is also a candidacy point worth stating plainly. SMILE Pro and LASIK both remove corneal tissue. A cornea too thin to support LASIK safely is also too thin to support SMILE Pro, so a patient who is not a LASIK candidate is generally not a SMILE Pro candidate either. When corneal thickness is the limiting factor, EVO ICL™ is usually the better option, because it removes no corneal tissue at all, and in some cases PRK is appropriate. My preference is WaveLight® Plus LASIK for good LASIK candidates and EVO ICL for those who are not.

Advocates of SMILE Pro highlight its flapless architecture as a potential advantage for patients with significant eye-trauma exposure, such as active-duty military personnel and contact-sport athletes. Our practice position is different. For patients whose work or sport carries meaningful risk of eye trauma, including MMA fighters and other combat athletes, Dr. Feinerman typically recommends PRK, a surface procedure that creates no flap and no cap interface at all. Advocates also highlight SMILE Pro’s smaller incision as a potential dry eye advantage over LASIK. Here again, our practice position is different. For patients with meaningful dry eye risk, whether mild or moderate to severe, Dr. Feinerman typically recommends evaluation for EVO ICL™, or postponing surgery until the ocular surface is controlled. EVO ICL™ removes no corneal tissue and leaves corneal nerves largely undisturbed, which makes it a better starting point for a vulnerable ocular surface than any corneal laser procedure. In a published study of patients 5 to 15 years after surgery, laser vision correction patients showed significantly higher rates of tear hyperosmolarity, a marker of tear film instability, than non-surgical controls, while implantable collamer lens patients showed no difference from controls (Gjerdrum B, et al. Clin Ophthalmol. 2020;14:269-279). For most refractive candidates, the math favors LASIK.

What to Ask Your SMILE Pro Surgeon Before Surgery

If you are considering SMILE Pro at any practice in Orange County or Los Angeles, these are the questions worth asking before you commit:

1. What enhancement technique do you use if I need a touch-up? If the answer involves CIRCLE software, ask explicitly whether they are using FDA-cleared CIRCLE (they cannot be) or an off-label pseudo-Circle workaround.
2. What is your enhancement rate for SMILE Pro patients specifically? Industry-wide rates are under 4%, but practice-level rates vary.
3. Do you offer lifetime enhancement coverage, and what does it cover? Some practices include cap-to-flap or thin-flap LASIK enhancement in lifetime coverage, others only cover PRK enhancement. The difference in patient experience is meaningful.
4. What happens if I end up hyperopic after SMILE Pro? SMILE Pro cannot treat hyperopia. Your enhancement options narrow significantly.
5. Why are you recommending SMILE Pro over WaveLight® Plus LASIK for my specific eyes? A clinically defensible answer should be grounded in your specific ocular surface findings, corneal measurements, and lifestyle, not generic SMILE Pro marketing claims. If the recommendation rests on eye-trauma exposure, ask why PRK, which creates no flap or cap interface, was not considered. If it rests on dry eye concerns, ask why EVO ICL™, which removes no corneal tissue, was not considered.

The Bottom Line

SMILE Pro enhancement in the United States is a constrained, off-label-heavy area of refractive surgery. The technique that international surgeons rely on (CIRCLE software) is not available to American practitioners. The remaining four pathways each carry meaningful drawbacks. American patients who choose SMILE Pro should understand this limitation before surgery, not after.

LASIK enhancement, by contrast, is one of the most predictable procedures in modern ophthalmology. It uses the same technology and the same anatomy as the original treatment. It treats all common refractive errors. Recovery is fast. Lifetime enhancement coverage actually means peace of mind.

For most patients in Orange County, this is one more reason that WaveLight® Plus LASIK is the stronger overall refractive choice. And for patients who are not LASIK candidates, the answer is not SMILE Pro, which removes corneal tissue under the same constraints and adds the enhancement limitations described above. It is EVO ICL™, which removes no corneal tissue, is reversible, and preserves every future option, or PRK, a surface procedure with no flap and no cap. The right answer for your eyes depends on your specific situation. A thorough consultation includes a discussion of enhancement pathways, not just primary procedure outcomes.

For the broader evidence-based comparison of SMILE Pro vs. LASIK safety across all dimensions, see Is SMILE Pro Safer Than LASIK? What the Evidence Actually Shows.

For the day-by-day recovery comparison, see SMILE Pro Recovery vs. LASIK Recovery: A Day-by-Day Comparison.

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Frequently Asked Questions

How common are enhancements after SMILE Pro?
Per data presented at the American Academy of Ophthalmology October 2025 meeting, enhancement rates after SMILE are under 4%. Risk factors for higher rates include older age and higher preoperative manifest refraction. Most enhancements occur within the first year after the original procedure.

Why is SMILE Pro enhancement more complicated than LASIK enhancement?
LASIK enhancement is a standard procedure: the original flap is lifted, the excimer laser fine-tunes the correction, and the flap is replaced. SMILE Pro does not create a flap, so enhancement requires either PRK on top of the cap, creation of a new thin or thick LASIK flap, or tricking the laser to perform cap-to-flap conversion. All three carry significant risks. The Zeiss CIRCLE software designed for SMILE enhancement is not available in the United States.

What is the Zeiss CIRCLE software, and why is it not available in the US?
CIRCLE is a Zeiss proprietary software package that converts a SMILE cap into a LASIK flap for enhancement. It is available in Europe, Asia, and other markets. It has not been approved by the FDA for use in the United States. American surgeons who want to perform cap-to-flap enhancement must trick the laser using an off-label workaround called pseudo-Circle, which carries additional risk because it lacks the vertical junction cut included in CIRCLE software.

What is the pseudo-Circle technique?
Pseudo-Circle is an off-label US workaround for the unavailable CIRCLE software. The surgeon programs the VisuMax femtosecond laser to create a LASIK flap, intentionally breaks suction during the cut, and re-docks to complete only the vertical side cut, effectively converting the SMILE cap into a LASIK flap. Peer-reviewed literature describes this technique as off-label for any primary refractive procedure enhancement.

What happens if a SMILE Pro patient ends up with hyperopia after surgery?
SMILE Pro is FDA approved only for myopia and myopic astigmatism, not hyperopia. A SMILE Pro patient with post-operative hyperopia cannot be enhanced with the SMILE Pro laser. Their options are PRK over the cap or off-label flap-conversion enhancement on an excimer laser. A LASIK patient in the same situation is treated with a standard hyperopic LASIK enhancement.

Does PRK over a SMILE cap have higher haze risk than primary PRK?
Yes. Mitomycin C is mandatory during PRK over a previous SMILE cap to prevent haze, and even with mitomycin C, published series report approximately 2.5% risk of postoperative corneal haze, which is meaningfully higher than primary PRK.

Does Feinerman Vision offer lifetime enhancement coverage?
Yes. All primary LASIK procedures at Feinerman Vision (both Wavefront-Optimized LASIK and WaveLight® Plus LASIK) include lifetime enhancement coverage. If your eyes change over time and you need a touch-up, the enhancement is provided at no additional cost as long as you have remained under our care.

Why does Feinerman Vision recommend WaveLight® Plus LASIK over SMILE Pro for most patients?
The combination of WaveLight® Plus’s superior visual outcomes per the Kanellopoulos October 2025 head-to-head study and LASIK’s simpler, more predictable enhancement pathway makes WaveLight® Plus LASIK the stronger choice for the vast majority of refractive candidates. For patients with significant eye-trauma exposure, such as active-duty military personnel or contact-sport athletes, Dr. Feinerman typically recommends PRK, which creates no flap or cap interface. For patients with meaningful dry eye risk, he typically recommends evaluation for EVO ICL™, which removes no corneal tissue and leaves corneal nerves largely undisturbed.

If I’m not a LASIK candidate, am I a SMILE Pro candidate?
Usually not. SMILE Pro and LASIK both remove corneal tissue. When LASIK is ruled out because the cornea is too thin, SMILE Pro is generally ruled out for the same reason. Two options are worth evaluating instead. EVO ICL removes no corneal tissue at all, which often makes it the better choice for thin corneas, higher prescriptions, and meaningful dry eye risk. PRK is a surface treatment that creates no flap. Which one fits depends on your corneal thickness and topography, your prescription, and your tear film, all of which are measured at your consultation.