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High AstigmatismNCT07446751

Long-term Outcomes of SMILE PRO for High Astigmatism

A study testing SMILE PRO surgery in people with High Astigmatism, run by Hanoi Medical University at 1 site in Vietnam.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This prospective interventional study aims to evaluate the long-term refractive and visual quality outcomes of SMILE PRO surgery in patients with myopia and high astigmatism. Eligible participants undergo small incision lenticule extraction using the VisuMax 800 femtosecond laser. Read more about this study

Who is it for?
Ages 18 to 40 years
Conditions the study is for
High Astigmatism
What is being tested?
SMILE PRO surgery
Type of treatment
Surgery or procedure
Could I receive a placebo?
No, everyone receives an active treatment
How many people
113 participants
Where
1 siteVietnam
Study dates
10 Dec 2024to Oct 2026
Phase
Interventional
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 40 years
  • All sexes
  • No healthy volunteers
  • Adult

Who may be able to join

  • Patients aged 18 to 40 years at the time of surgery
  • Diagnosis of myopia with high astigmatism eligible for SMILE PRO surgery
  • Stable refractive error prior to surgery
  • Adequate corneal thickness and topographic parameters suitable for SMILE PRO
  • Ability to understand the study procedures and provide written informed consent
  • Willingness and ability to attend scheduled postoperative follow-up visits

Who cannot join

  • Presence of corneal ectatic disorders or suspicious corneal topography
  • History of previous ocular surgery or ocular trauma
  • Active ocular disease other than refractive error
  • Systemic diseases known to affect wound healing
  • Pregnancy or breastfeeding at the time of surgery

Trial locations and contacts

1 site in 1 country.

Vietnam1 site

  • Hong Son Eye Hospital

    Hanoi, Hanoi, 100000

Other trials in Vietnam

About this study

Official title: Outcomes of SMILE PRO Surgery for the Correction of Myopia With High Astigmatism

This prospective interventional study aims to evaluate the long-term refractive and visual quality outcomes of SMILE PRO surgery in patients with myopia and high astigmatism. Eligible participants undergo small incision lenticule extraction using the VisuMax 800 femtosecond laser. Postoperative assessments include uncorrected and corrected distance visual acuity, manifest refraction, astigmatic vector analysis, contrast sensitivity, and higher-order aberrations. Participants are followed for up to 12 months to assess refractive accuracy, stability, safety, and visual quality after surgery.

Read the detailed description

This is a single-center, prospective interventional clinical study conducted to assess the long-term refractive and visual quality outcomes of SMILE PRO surgery for the correction of myopia with high astigmatism. The study is performed at Hong Son Eye Hospital, Vietnam, following approval from the Institutional Review Board of Hanoi Medical University. All participants provide written informed consent prior to enrollment.

Patients aged 18 to 40 years with stable myopic refractive error and high astigmatism are eligible for inclusion. All eyes undergo small incision lenticule extraction using the VisuMax 800 femtosecond laser according to a standardized surgical protocol. Manifest refraction, corneal topography, and ocular imaging are performed by experienced refractive technicians using standardized measurement protocols. All patients are examined preoperatively and postoperatively by an ophthalmologist, who reviews clinical findings and surgical eligibility. All SMILE PRO procedures are performed by the same ophthalmic surgeon to minimize variability related to surgical technique.

Outcome measures include uncorrected and corrected distance visual acuity, spherical equivalent refraction, residual refractive astigmatism, and astigmatic vector analysis based on the Alpins method. Visual quality outcomes are further evaluated using contrast sensitivity testing and wavefront aberrometry to assess higher-order aberrations. Intraoperative parameters, including centration and cyclotorsion, are recorded and analyzed for their potential association with postoperative refractive outcomes.

Postoperative examinations are performed at 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. The primary objective of this study is to evaluate the long-term refractive accuracy, stability, and safety of SMILE PRO surgery in eyes with high astigmatism. Secondary objectives include the assessment of preoperative and intraoperative factors influencing postoperative visual and refractive outcomes.

Being tested
SMILE PRO surgery
Keywords
SMILE PRO, High astigmatism, Small incision lenticule extraction, Astigmatic vector analysis, Cyclotorsion, Higher-order aberrations, Contrast sensitivity

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • SMILE PRO surgeryProcedure or surgery

    Small incision lenticule extraction surgery performed using the VisuMax 800 femtosecond laser (SMILE PRO) for the correction of myopia with high astigmatism. The procedure is performed by a single experienced ophthalmic surgeon following a standardized surgical protocol.

Study groups in NCT07446751
Study groupRoleWhat they receive
SMILE PRO surgeryExperimentalParticipants with myopia and high astigmatism undergoing small incision lenticule extraction using the SMILE PRO surgery.
Receives: Procedure: SMILE PRO surgery

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Residual Refractive Astigmatism

    Residual refractive astigmatism was measured using manifest refraction and analyzed with astigmatic vector analysis based on the Alpins method.

    Measured: 12 months postoperatively

  2. Refractive Accuracy (Spherical Equivalent Error)

    Refractive accuracy was assessed using manifest refraction spherical equivalent (SEQ) after SMILE PRO surgery.

    Measured: 12 months postoperatively

Secondary outcomes (13)

  1. Refractive Stability Over Time (Spherical Equivalent)

    Manifest refraction spherical equivalent (SEQ) was measured at each postoperative visit to evaluate refractive stability.

    Measured: 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively

  2. Refractive Cylinder Over Time

    Manifest refractive cylinder was measured using subjective refraction and expressed in diopters (D) at scheduled postoperative visits following SMILE Pro surgery. This outcome evaluates the magnitude and stability of residual astigmatism during the 12-month follow-up period.

    Measured: 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively

  3. Uncorrected Distance Visual Acuity (UDVA)

    Uncorrected distance visual acuity was measured using standardized logMAR charts.

    Measured: 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively

  4. Corrected Distance Visual Acuity (CDVA)

    Corrected distance visual acuity was assessed to evaluate visual safety after surgery.

    Measured: 1 month, 3 months, 6 months, and 12 months postoperatively

  5. Surgically Induced Astigmatism (SIA)

    Surgically induced astigmatism, expressed in diopters (D), represents the vector magnitude of astigmatic change produced by surgery. It was calculated using the Alpins vector analysis method by comparing preoperative and postoperative refractive cylinder magnitude and axis.

    Measured: 3 months and 12 months postoperatively

  6. Target Induced Astigmatism (TIA)

    Target induced astigmatism, expressed in diopters (D), represents the vector magnitude of astigmatic correction intended by the surgical plan. It was calculated using the Alpins vector analysis method based on the preoperative refractive cylinder magnitude and the planned axis of correction.

    Measured: 3 months and 12 months postoperatively

  7. Difference Vector (DV)

    Difference vector (DV), expressed in diopters (D), represents the vector magnitude of residual astigmatism that would need to be corrected to achieve the intended target. It was calculated using the Alpins vector analysis method based on postoperative refractive cylinder magnitude and axis relative to the planned correction.

    Measured: 3 months and 12 months postoperatively

  8. Correction Index (CI)

    Correction index, expressed as a unitless ratio, represents the ratio of surgically induced astigmatism to target induced astigmatism. It was calculated using the Alpins vector analysis method to quantify the accuracy of astigmatic correction. A value of 1.0 indicates exact correction, values greater than 1.0 indicate overcorrection, and values less than 1.0 indicate undercorrection.

    Measured: 3 months and 12 months postoperatively

  9. Angle of Error (AE)

    Angle of error, expressed in degrees (°), represents the angular difference between the achieved astigmatic correction and the intended target axis. It was calculated using the Alpins vector analysis method based on the deviation between the axis of surgically induced astigmatism and the planned treatment axis. Positive and negative values indicate counterclockwise and clockwise deviations from the intended axis, respectively.

    Measured: 3 months and 12 months postoperatively

  10. Higher-Order Aberrations

    Ocular higher-order aberrations were measured using wavefront aberrometry to assess postoperative visual quality.

    Measured: 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively.

  11. Contrast Sensitivity

    Contrast sensitivity was evaluated under photopic conditions to assess functional visual quality.

    Measured: 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively

  12. Lenticule Decentration

    Lenticule decentration is defined as the linear displacement between the intended lenticule center and the corneal vertex during SMILE PRO surgery. This parameter is automatically recorded intraoperatively by the CentraLign software integrated into the VisuMax 800 femtosecond laser system, based on real-time centration alignment guidance. Decentration is quantified as a continuous variable and expressed in millimeters (mm). For descriptive analysis, decentration values are categorized as < 0.1 mm, 0.1-0.19 mm, and ≥ 0.2 mm. For regression analyses, the continuous decentration value (mm) is used.

    Measured: Intraoperative

  13. Intraoperative Cyclotorsion

    Intraoperative cyclotorsion is defined as the rotational misalignment (in degrees) between the preoperative reference axis obtained from iris registration and the intraoperative axis detected during docking using the OcuLign and CentraLign systems integrated into the VisuMax 800 platform. Cyclotorsion is recorded automatically by the system in degrees (°). Negative values indicate clockwise rotation and positive values indicate counterclockwise rotation. The magnitude of cyclotorsion is analyzed in relation to postoperative refractive outcomes.

    Measured: Intraoperative

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 Mar 2026
  2. Study start10 Dec 2024
  3. Primary completionOct 2026 (estimated)
  4. Study completionOct 2026 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
113 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07446751
Sponsor's protocol ID
#HMUIRB1649#
Status last verified
Feb 2026
First submitted
10 Feb 2026
Last updated
3 Mar 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: De-identified individual participant data underlying the results reported in this study will be made available. Shared data will include demographic characteristics, preoperative and postoperative refractive outcomes, visual acuity measurements, astigmatic vector parameters, contrast sensitivity results, and wavefront-derived higher-order aberrations. No personally identifiable information will be shared.

Publications

  • Reinstein DZ, Archer TJ, Potter JG, Gupta R, Wiltfang R. Refractive and Visual Outcomes of SMILE for Compound Myopic Astigmatism With the VISUMAX 800. J Refract Surg. 2023 May;39(5):294-301. doi: 10.3928/1081597X-20230301-02. Epub 2023 May 1.

    PubMed 37162399

  • Pedersen IB, Ivarsen A, Hjortdal J. Changes in Astigmatism, Densitometry, and Aberrations After SMILE for Low to High Myopic Astigmatism: A 12-Month Prospective Study. J Refract Surg. 2017 Jan 1;33(1):11-17. doi: 10.3928/1081597X-20161006-04.

    PubMed 28068441

  • Chan TCY, Wang Y, Ng ALK, Zhang J, Yu MCY, Jhanji V, Cheng GPM. Vector analysis of high (>/=3 diopters) astigmatism correction using small-incision lenticule extraction and laser in situ keratomileusis. J Cataract Refract Surg. 2018 Jul;44(7):802-810. doi: 10.1016/j.jcrs.2018.04.038. Epub 2018 Jun 13.

    PubMed 29909252

  • Zhou J, Gu W, Gao Y, He G, Zhang F. Vector analysis of high astigmatism (>/= 2.0 diopters) correction after small-incision lenticule extraction with stringent head positioning and femtosecond laser-assisted laser in situ keratomileusis with compensation of cyclotorsion. BMC Ophthalmol. 2022 Apr 5;22(1):157. doi: 10.1186/s12886-022-02384-0.

    PubMed 35382779

Questions about this trial

What is this clinical trial studying?

A study testing SMILE PRO surgery in people with High Astigmatism, run by Hanoi Medical University at 1 site in Vietnam.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 3 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Vietnam. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Residual Refractive Astigmatism (time frame: 12 months postoperatively). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07446751, which also lists 4 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Mar 2026.

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