LASIK vs PRK vs SMILE.
In a 750-eye head-to-head study, 95 percent of LASIK, 94 percent of PRK, and 94 percent of SMILE patients achieved 20/20 uncorrected vision at 6 months with no statistically significant difference (Hagan 2024, PMID 39641610). Choice is driven by candidacy gates and risk profile, not raw efficacy: SMILE preserves corneal biomechanics significantly better than LASIK and causes less dry eye, but matches PRK on biomechanics. PRK is the right answer for thin corneas and high-impact lifestyles.
The three procedures, compared.
| LASIK | PRK | SMILE | |
|---|---|---|---|
| 20/20 UDVA | 95% | 94% | 94% |
| FDA range (myopia) | to −10 D | to −10 D | −1 to −10 D |
| Astigmatism max | −6 D | −6 D | −3 D |
| Min CCT | ~500 µm | ~460 µm | >475 µm |
| Flap | Yes (~20 mm) | None | Small incision (2-4 mm) |
| Dry eye at 1 month | 60-70% | Lower than LASIK | Lower than LASIK |
| Visual recovery | 24-48 h | 4-7 days | 1-3 days |
| Pain | Minimal | Significant 3-5 days | Minimal |
| Cost (US per eye) | $2,000-3,500 | $1,800-3,200 | $2,500-4,000 |
Numbers from Hagan 2024 (PMID 39641610), StatPearls NBK549896, PMC11110473, FDA P150040C. Cost ranges are orientation only (cost pillar carries verified per-chain figures).
20/20 success rates are statistically tied.
The largest recent head-to-head comparison in the United States is Hagan et al. 2024, a retrospective study of 750 eyes (118 LASIK, 550 PRK, 82 SMILE) in active-duty military personnel treated 2004 to 2019. Across all three procedures, patients achieving 20/20 or better uncorrected distance vision at 6 months were:
- LASIK: 95 percent
- PRK: 94 percent
- SMILE: 94 percent
P value for the difference: 0.308. In plain English, the difference is not statistically meaningful. Patient-reported night vision (P = 0.505) and glare (P = 0.258) were also statistically equivalent at 6 months. The authors concluded that all three procedures yield excellent visual outcomes with minimal visual symptoms.
Caveat: the cohort is young, healthy, and followed only 6 months. Longer follow-up and older-patient data is thinner. For a routine myope in modern hands, the procedures deliver comparable acuity. Procedure selection is therefore driven by candidacy gates and risk profile, not by the question "which gives the best vision."
The cornea decides for many patients.
LASIK creates a thin corneal flap (typically 100 to 110 µm) with a femtosecond laser, lifts the flap, then sculpts the underlying stroma with an excimer laser. PRK skips the flap entirely: the surgeon removes the corneal epithelium (the surface skin layer), then sculpts the same stroma directly. SMILE uses the femtosecond laser to create a thin lens-shaped piece of stroma (a lenticule) inside the cornea, then extracts it through a 2 to 4 mm incision.
All three need to leave a safe residual stromal bed after ablation. The widely cited minimum is 250 µm; many surgeons prefer 300 µm. Because LASIK uses corneal tissue for the flap before any reshaping, it requires the thickest starting cornea. PRK works with the thinnest. SMILE sits in between.
If your corneal thickness puts LASIK borderline, the conversation is usually PRK or SMILE. If your topography shows any sign of keratoconus or forme fruste keratoconus, all three corneal lasers are off the table; ICL becomes the alternative.
Why "biomechanical preservation" matters.
Refractive surgery removes corneal tissue. That removal weakens the cornea's resistance to deformation. The question is how much, and how it compares between procedures. Guo et al. 2019 (PMC6676534) pooled 22 studies including 5 randomized controlled trials and reported:
- SMILE vs LASIK: Hedges g = 1.31 (95 percent CI 0.54 to 2.08, p < 0.001). Large effect. SMILE preserves significantly more biomechanical strength.
- SMILE vs femtosecond LASIK: g = 0.41 (CI 0.00 to 0.81, p = 0.049). Modest, borderline significance.
- SMILE vs PRK/LASEK: g = -0.26 (CI -0.67 to 0.16, p = 0.230). No significant difference. Surface ablation matches SMILE.
Two practical takeaways. First, SMILE's biomechanical advantage over LASIK is real and large. Second, surface ablation (PRK, LASEK) achieves the same preservation as SMILE; the SMILE marketing message about biomechanics is true relative to LASIK but not relative to PRK. Caveat: heterogeneity in the meta-analysis was high (I squared ~77 to 78 percent), and corneal hysteresis and corneal resistance factor are imperfect biomechanical surrogates.
"20/20 is guaranteed."
It is not. In modern hands, 94 to 95 percent of suitable candidates achieve 20/20 uncorrected vision at 6 months (Hagan 2024). That means 5 to 6 percent do not. Some require a touch-up enhancement; some live with a residual prescription correctable by glasses; a small number have a complication that limits best-corrected vision. The FDA prohibits clinics from advertising guaranteed outcomes. If you see a guarantee, ask why.
"SMILE has no dry eye."
Refuted. About 60 to 70 percent of LASIK patients report dry eye symptoms at 1 month (PMC11110473). Chronic rates at 6 months and beyond fall to 20 to 40 percent. SMILE produces fewer dry-eye symptoms than LASIK because its 2 to 4 mm incision severs fewer corneal nerves than a ~20 mm LASIK flap; confocal microscopy confirms faster nerve regeneration (PMC5161410, PMC5406644). But SMILE does not eliminate dry eye. The mechanism reduces, not erases. SMILE patients still experience dry eye, just at a meaningfully lower rate.
When PRK or SMILE win on lifestyle alone.
Even when a patient is a candidate for all three procedures, lifestyle can flip the decision.
- Contact sports, martial arts. A LASIK flap can be displaced years after surgery by a hard blow to the eye. PRK and SMILE remove that risk because there is no flap. Many military and first-responder programs prefer or require PRK or SMILE for this reason.
- Heavy screen use, dry climate, contact-lens-related dry eye history. SMILE or PRK is the gentler choice on the corneal nerves. LASIK can still be performed safely with aggressive dry-eye prep, but the bar is higher.
- Younger patients (early 20s). SMILE's age floor is 22, and many surgeons prefer to wait until 24 to 25 for refractive stability. PRK and LASIK have an FDA floor of 18 but the same stability rule applies.
- Heavy night driving. All three procedures can produce halos and starbursts at night, particularly in the first 3 to 6 months. Mesopic pupil size relative to the optical zone is the determinant; small optical zones in older devices were the historical problem. Modern devices have largely solved this.
A clean way to think about it.
- If your cornea is thin or your topography is borderline, PRK first, then SMILE, with LASIK off the table.
- If you have moderate dry eye history, SMILE or PRK, not LASIK.
- If you do contact sports, martial arts, or military duty, PRK or SMILE, not LASIK.
- If none of the above, LASIK and SMILE are clinically equivalent and LASIK usually costs less. Pick on cost or on whichever surgeon you trust most.
- If your prescription exceeds the laser FDA range (above −10 D myopia, above +5 D hyperopia, above −6 D astigmatism), the conversation shifts to EVO ICL. See the candidacy guide.
Tell us about your eyes.
Frequently asked questions
Is SMILE better than LASIK?
Not for raw visual outcomes. In a 750-eye head-to-head study (Hagan 2024, PMID 39641610), 95 percent of LASIK and 94 percent of SMILE patients achieved 20/20 with no statistically significant difference. SMILE does have measurably less dry eye than LASIK because its 2 to 4 mm incision severs fewer corneal nerves, and SMILE preserves corneal biomechanics significantly better (Hedges g = 1.31, p < 0.001, PMC6676534). For a patient with a borderline cornea or moderate dry eye history, SMILE is often the better answer. For a straightforward myope with a healthy cornea and no dry eye history, LASIK and SMILE are clinically equivalent and LASIK costs less.
Why would I choose PRK over LASIK?
Three reasons. First, your cornea is thinner than LASIK requires for a safe residual stromal bed but thick enough for PRK (which removes no flap). Second, your lifestyle involves contact sports, military service, or a job where a flap could be displaced; PRK has no flap. Third, you want maximum long-term biomechanical strength; PRK and SMILE preserve biomechanics better than LASIK (PMC6676534). The trade-off is recovery. PRK is painful for 3 to 5 days and visual recovery takes weeks, not days.
Does SMILE really cause less dry eye?
Yes, but it does not eliminate dry eye. About 60 to 70 percent of LASIK patients report dry eye at 1 month, with chronic rates of 20 to 40 percent at 6 months and beyond (PMC11110473). SMILE has lower incidence because the small 2 to 4 mm incision severs fewer sub-basal corneal nerves than a ~20 mm LASIK flap, and confocal microscopy confirms faster nerve regeneration (PMC5161410, PMC5406644). The marketing line "SMILE has no dry eye" is refuted. SMILE has less, not none.
Which has the fastest recovery, LASIK, PRK, or SMILE?
LASIK has the fastest visual recovery: most patients see well within 24 to 48 hours and return to work within 1 to 2 days. SMILE is similar or slightly slower at 1 to 3 days. PRK is the slowest. The epithelium has to regrow over the treated surface, which takes 4 to 7 days, with significant discomfort and blurred vision during that window. Full visual stability with PRK can take 3 to 6 months.
Is the 20/20 success rate really the same for all three?
In the Hagan 2024 study of 750 US military eyes treated 2004 to 2019, yes: 95 percent LASIK, 94 percent PRK, 94 percent SMILE (P = .308 for the difference). Patient-reported night vision (P = .505) and glare (P = .258) were also statistically equivalent at 6 months. The caveat is the population: young, healthy, and followed only 6 months. Long-term and older-patient data is thinner. But for the question "do all three deliver 20/20", the answer in modern hands is yes.
Sources cited on this page
- Hagan W et al. Comparative outcomes of LASIK, PRK, and SMILE in US military, 2004-2019. PubMed 39641610.
- Shen Z et al. SMILE vs FS-LASIK for high myopia: meta-analysis. PMC7870077.
- Guo H et al. Corneal biomechanical changes after refractive surgery: meta-analysis. PMC6676534.
- Comprehensive review of LASIK, SMILE, and ICL outcomes. PMC11110473.
- Dry eye after SMILE vs LASIK: confocal microscopy. PMC5161410, PMC5406644.
- StatPearls: Small Incision Lenticule Extraction (SMILE). NBK549896.
- FDA. ZEISS VisuMax Patient Information Booklet. P150040C.
- American Academy of Ophthalmology. Refractive Errors and Refractive Surgery PPP (2025).
Educational content only. Not medical advice. Final candidacy requires in-person ophthalmologist exam with topography, pachymetry, and biometry. We do not accept clinic sponsorship or referral commissions.