Ocular Evidence
Procedures / SMILE
Corneal lenticule

SMILE outcomes

A femtosecond laser creates an intrastromal lenticule corresponding to the refractive correction, which is removed through a small opening incision.

Source: FDA Summary of Safety and Effectiveness Data — P150040
Find overlapping cohorts
16studies represented
16study arms
11,707reported enrolled eyes*
5 yearslongest standardized follow-up

* Descriptive sum of reported arm counts. Missing eye counts are not treated as zero, and overlapping cohorts may not be additive.

How the operation changes the eye
Three-stage medical illustration showing a corneal lenticule created and removed through a small incision during SMILE
Original explanatory illustration. Simplified anatomy; exact devices and technique vary.
How the operation works

A small piece of tissue is removed through a keyhole incision

SMILE changes corneal curvature without making a LASIK-style flap or using an excimer laser.

  1. A femtosecond laser creates a lens-shaped piece of tissue, called a lenticule, inside the cornea.
  2. The same laser creates a small opening at the edge of the cornea.
  3. The surgeon separates and removes the lenticule through that opening, changing the cornea’s shape.
Clinical reference: US FDA — SMILE patient information booklet

Study-specific outcomes

Percentages are displayed individually. They are not pooled or averaged.

LOW evidenceMETA ANALYSISVerified evidence

Small-Incision Lenticule Extraction with Prophylactic Cross-Linking: A Systematic Review and Meta-Analysis (2026)

KLEx versus KLEx with prophylactic cross-linking730 enrolled eyesDevice not reported
Pooled follow-up730 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
0.03 D
9 studies
Source · Abstract
Residual MRSE mean difference
1 monthFollow-up sample not reported
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
-0.040 logMARSource · Abstract
Uncorrected distance vision mean difference
Safety index mean difference
Efficacy index mean difference
MODERATE evidenceMETA ANALYSISVerified evidence

Effects of SMILE on intraocular pressure and corneal biomechanics: a systematic review and meta-analysis (2026)

SMILE pooled observational evidence1,177 enrolled eyesDevice not reported
Pooled postoperative follow-up1177 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Measured IOP reduction with GAT
Measured IOP reduction with ORA
Measured IOP reduction with Corvis ST
LOW evidenceRETROSPECTIVEVerified evidence

Comparison of Persistent Postoperative Discomfort 1 Year after Keratorefractive Lenticule Extraction and Implantable Collamer Lens Implantation (2025)

Keratorefractive lenticule extraction (KLEX)227 enrolled eyesVisuMax Femtosecond Laser
1 year227 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Postoperative night glare
Postoperative halos
MODERATE evidenceRETROSPECTIVEVerified evidence

Visual outcomes for the initial 500 eyes treated with keratorefractive lenticule extraction for myopia and myopic astigmatism at a single site (2025)

KLEx577 enrolled eyesDevice not reported
12 months440 eyes observed
81.0%
440 eyes
Source
Uncorrected 20/20 or better
85.0%
440 eyes
Source
Refraction within ±0.50 D
97.0%
440 eyes
Source
Refraction within ±1.00 D
0%
0/440 eyes
Source
Lost at least 2 lines of CDVA
Additional source-reported outcomes
0.04 DSource
Mean postoperative spherical equivalent
LOW evidenceRETROSPECTIVEVerified evidence

Myopic Regression After FS-LASIK and SMILE (2024)

Matched SMILE cohort416 enrolled eyesDevice not reported
3 months416 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Spherical-equivalent regression from month 1
6 months416 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Spherical-equivalent regression from month 1
9 months416 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Spherical-equivalent regression from month 1
12 months416 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Spherical-equivalent regression from month 1
18 months416 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Spherical-equivalent regression from month 1
LOW evidenceRETROSPECTIVEVerified evidence

Small incision lenticule extraction (SMILE) refractive surgery: Our initial experience (2022)

SMILE Armed Forces cohort202 enrolled eyesDevice not reported
1 day202 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Mean uncorrected distance visual acuity
1 week202 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Mean uncorrected distance visual acuity
1 month202 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Mean uncorrected distance visual acuity
3 months202 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Mean uncorrected distance visual acuity
MODERATE evidencePROSPECTIVE COHORTVerified evidence

Two-Year Visual Outcomes of Evolution Implantable Collamer Lens and Small Incision Lenticule Extraction for the Correction of Low Myopia (2022)

SMILE36 enrolled eyesVisuMax Femtosecond Laser
2 years36 eyes observed
Not reportedUncorrected 20/20 or better
94.4%
34/36 eyes
Source
Refraction within ±0.50 D
Not reportedRefraction within ±1.00 D
0%
0/36 eyes
Source
Lost at least 2 lines of CDVA
Additional source-reported outcomes
88.9%
32/36 eyes
Source
Uncorrected acuity at least as good as preoperative corrected acuity
HIGH evidenceRCTVerified evidence

Randomized Clinical Trial Comparing Femtosecond LASIK and Small-Incision Lenticule Extraction (2020)

SMILE70 enrolled eyesVisuMax Femtosecond Laser
3 months70 eyes observed
84.0%
70 eyes
Source
Uncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
99.0%
70 eyes
Source
Refraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Efficacy index
Safety index
12 months70 eyes observed
85.0%
70 eyes
Source
Uncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
99.0%
70 eyes
Source
Refraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Safety index
MODERATE evidencePROSPECTIVE COHORTVerified evidence

Small Incision Lenticule Extraction for Hyperopia: 12-Month Refractive and Visual Outcomes (2019)

Hyperopic SMILE93 enrolled eyesVisuMax Femtosecond Laser
12 months72 eyes observed
Not reportedUncorrected 20/20 or better
53.0%
37 eyes
Source
Refraction within ±0.50 D
Not reportedRefraction within ±1.00 D
0%
0/72 eyes
Source
Lost at least 2 lines of CDVA
Additional source-reported outcomes
-0.19 DSource
Mean postoperative spherical equivalent
16.0%
72 eyes
Source
Loss of 1 line of corrected visual acuity
LOW evidenceRETROSPECTIVEVerified evidence

Visual outcomes 5 years after small incision lenticule extraction (SMILE), surgery on spherocylindrical myopia eyes, from 616 eyes (2018)

VisuMax SMILE616 enrolled eyesVisuMax Femtosecond Laser
5 yearsFollow-up sample not reported
Not reportedUncorrected 20/20 or better
Refraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
Uncorrected distance vision 20/25 or better
Lost no lines of CDVA
HIGH evidenceFDA PIVOTALVerified evidence

FDA pivotal clinical study of SMILE with the VisuMax Femtosecond Laser (2016)

VisuMax SMILE336 enrolled eyesVisuMax Femtosecond Laser
6 months328 eyes observed
87.5%
287/328 eyes
Source · 23
Uncorrected 20/20 or better
93.0%
305/328 eyes
Source · 23
Refraction within ±0.50 D
98.5%
323/328 eyes
Source · 24
Refraction within ±1.00 D
0%
0/329 eyes
Source · 15
Lost at least 2 lines of CDVA
12 months310 eyes observed
88.1%
273/310 eyes
Source · 23
Uncorrected 20/20 or better
93.9%
291/310 eyes
Source · 23
Refraction within ±0.50 D
98.7%
306/310 eyes
Source · 24
Refraction within ±1.00 D
0%
0/311 eyes
Source · 21
Lost at least 2 lines of CDVA
MODERATE evidencePROSPECTIVE COHORTVerified evidence

Dry Eye Disease following Refractive Surgery: A 12-Month Follow-Up of SMILE versus FS-LASIK in High Myopia (2015)

SMILE high-myopia cohort47 enrolled eyesDevice not reported
1 month47 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
6.28 s
47 patients
Source · Table 3
Tear breakup time
0.77
47 patients
Source · Table 4
Salisbury Eye Evaluation Questionnaire dry-eye score
3 months47 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
8.21 s
47 patients
Source · Table 3
Tear breakup time
0.34
47 patients
Source · Table 4
Salisbury Eye Evaluation Questionnaire dry-eye score
6 months47 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
9.57 s
47 patients
Source · Table 3
Tear breakup time
0.13
47 patients
Source · Table 4
Salisbury Eye Evaluation Questionnaire dry-eye score
12 months47 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
9.83 s
47 patients
Source · Table 3
Tear breakup time
0.04
47 patients
Source · Table 4
Salisbury Eye Evaluation Questionnaire dry-eye score
HIGH evidenceRCTVerified evidence

Comparison of visual and refractive outcomes following femtosecond laser-assisted LASIK with SMILE in patients with myopia or myopic astigmatism (2014)

SMILE50 enrolled eyesDevice not reported
1 day50 eyes observed
Uncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
3 months50 eyes observed
Uncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
MODERATE evidencePROSPECTIVE COHORTVerified evidence

Comparison of dry eye and corneal sensitivity between small incision lenticule extraction and femtosecond LASIK for myopia (2013)

SMILE38 enrolled eyesDevice not reported
1 week37 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
23.95
37 patients
Source · Table 3
Ocular Surface Disease Index
4.32 s
37 patients
Source · Table 3
Tear breakup time
13.51 mm
37 patients
Source · Table 3
Schirmer I test without anesthesia
1 month37 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
16.72
37 patients
Source · Table 3
Ocular Surface Disease Index
5.68 s
37 patients
Source · Table 3
Tear breakup time
12.11 mm
37 patients
Source · Table 3
Schirmer I test without anesthesia
3 months36 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
12.05
36 patients
Source · Table 3
Ocular Surface Disease Index
5.03 s
36 patients
Source · Table 3
Tear breakup time
14.14 mm
36 patients
Source · Table 3
Schirmer I test without anesthesia
6 months36 eyes observed
Not reportedUncorrected 20/20 or better
Not reportedRefraction within ±0.50 D
Not reportedRefraction within ±1.00 D
Not reportedLost at least 2 lines of CDVA
Additional source-reported outcomes
8.47
36 patients
Source · Table 3
Ocular Surface Disease Index
7.06 s
36 patients
Source · Table 3
Tear breakup time
13.28 mm
36 patients
Source · Table 3
Schirmer I test without anesthesia