An interventional study of Apply compensation to the Kappa angle. and Apply no compensation to the Kappa angle in Myopia and Refractive Ametropia, sponsored by Zhongshan Ophthalmic Center, Sun Yat-sen University. Recruiting at 1 site in China. Open to participants aged 18 Years to 40 Years. Per ClinicalTrials.gov, last updated 2026-07-07.
Sponsored by Zhongshan Ophthalmic Center, Sun Yat-sen University · Not applicable, Interventional, and Treatment
Help build ClinicalTrials.gg — short surveys, remote interviews or testing, in your language. Take part →
Among 24 studies in Myopia by Zhongshan Ophthalmic Center, Sun Yat-sen University — 12 open to participants now, 14 under way, none of them phase 3. Myopia · Zhongshan Ophthalmic Center, Sun Yat-sen University.
Among the 24 studies in Myopia by Zhongshan Ophthalmic Center, Sun Yat-sen University, this one is the 8th largest by planned enrollment of the 17 interventional ones that give a count, is one of 5 that started in 2026, is one of 17 with no phase, reaches primary completion later than 9 of the 13 other live ones, and was the 19th registered.
1,160 studies on the registry are indexed under Myopia; 225 are open to participants now.
Browse Myopia studies →12 of the 24 studies in Myopia by Zhongshan Ophthalmic Center, Sun Yat-sen University are open now, in 1 country. Recruiting first, the newest first:
Zhongshan Ophthalmic Center, Sun Yat-sen University · Sites in China
Ages 6–18 · Healthy volunteers
Zhongshan Ophthalmic Center, Sun Yat-sen University · Sites in China
Ages 18–40
Zhongshan Ophthalmic Center, Sun Yat-sen University · Sites in China
Ages 3–18 · Healthy volunteers
Zhongshan Ophthalmic Center, Sun Yat-sen University
Ages 8–13
Zhongshan Ophthalmic Center, Sun Yat-sen University · Sites in China
Ages 18–40
By country, each count listing its studies:
Of the 122 Myopia studies recruiting now, 19 (16%) set no upper age limit and 102 (84%) stop at 75 or younger; 86 take children under 18; 53 take healthy volunteers.
This study: 18 Years to 40 Years · all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
24 studies; the count open now beside each. This study's row is marked.
First in 2016; this study’s year is marked. 5 started in 2026.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 224 is above the median of 78 across 923 interventional studies indexed under Myopia.
Median enrollment 194 across the 17 interventional studies, 1,000 across the 7 observational. Of the 4 that completed or were terminated, 0 (0%) have results posted.
This tab as a report to print or save as PDF → With an account.
Zhongshan Ophthalmic Center, Sun Yat-sen University is the lead sponsor of 165 studies on the registry; 81 are open to participants now.
4 of the studies in Myopia by Zhongshan Ophthalmic Center, Sun Yat-sen University that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT06667037Zhongshan Ophthalmic Center, Sun Yat-sen UniversityOrthokeratology and 0.01% Atropine Sequential Treatment for Myopia Control | 2026-12-31 |
| NCT07512102Zhongshan Ophthalmic Center, Sun Yat-sen UniversityComparison of Low- Versus High-Level Angle Kappa Compensation Strategies in SMILE Using the VisuMax 800: A Randomized Clinical Trial | 2027-05-30 |
| NCT07512115Zhongshan Ophthalmic Center, Sun Yat-sen UniversityThe Impact of 'A Miss Is as Good as a Mile': Is Compensation Necessary for Minimal Ocular Deviation in Myopic Laser Surgery? | 2027-05-30 |
| NCT07696468Zhongshan Ophthalmic Center, Sun Yat-sen UniversityComparison of Two Rotational Alignment Methods for Astigmatism Correction in SMILE Surgery | 2027-06-30 |
Add all 4 to your calendar (.ics) → With an account.
Among the 24 studies in Myopia by Zhongshan Ophthalmic Center, Sun Yat-sen University, from their registry updates:
This tab as a report to print or save as PDF → With an account.
The goal of this clinical trial is to evaluate the effect of intraoperative kappa-angle compensation on postoperative visual quality in patients undergoing small incision lenticule extraction (SMILE) using the VisuMax 800 platform. The study will enroll patients with myopia and a kappa-angle offset \< 0.2 mm.
The main questions it aims to answer are:
Does intraoperative kappa-angle compensation reduce postoperative higher-order aberrations after SMILE? Does kappa-angle compensation improve postoperative visual quality and refractive outcomes compared with no compensation?
Researchers will compare SMILE with intraoperative kappa-angle compensation to SMILE without compensation to determine whether compensation leads to better optical quality and visual performance.
Participants will:
Undergo SMILE surgery with or without intraoperative kappa-angle compensation Complete scheduled postoperative examinations at 1 week, 1 month, 3 months, and 6 months after surgery Receive measurements of visual acuity, refraction, higher-order aberrations, contrast sensitivity, and safety outcomes
Angle kappa refers to the offset between the visual axis and the pupil center and may influence the centration of the treatment zone during corneal refractive surgery. Inaccurate centration can lead to decentered ablation and may affect postoperative visual quality, especially higher-order aberrations. With the development of femtosecond laser technology, more precise intraoperative alignment has become possible.
Small incision lenticule extraction (SMILE) is a commonly used corneal refractive procedure with good safety and predictability. The VisuMax 800 system incorporates machine vision-assisted centration guidance, which allows intraoperative adjustment of the treatment center according to the relative position of the corneal vertex and the pupil center. This provides the possibility of performing intraoperative compensation based on the kappa-angle offset.
Previous studies have mainly evaluated centration adjustment in eyes with relatively large kappa-angle offsets and suggested that compensation may improve postoperative optical quality. However, for patients with small offsets, the necessity of intraoperative compensation remains unclear, and prospective randomized clinical trials are limited.
The purpose of this study is to compare the visual outcomes and optical quality after SMILE with or without intraoperative kappa-angle compensation in patients with small kappa-angle offsets.
This study is a single-center, randomized, parallel-group clinical trial. Participants who are suitable for SMILE surgery and have a kappa-angle offset less than 0.2 mm will be enrolled and randomly assigned to receive SMILE with compensation or SMILE without compensation using the VisuMax 800 platform.
All surgeries will be performed by experienced surgeons using standard SMILE procedures. Participants will undergo routine ophthalmic examinations before surgery and will be followed after surgery at scheduled visits.
The main evaluation will assess postoperative visual quality and refractive outcomes. Additional assessments will include visual acuity, refractive accuracy, higher-order aberrations, contrast sensitivity, and safety outcomes.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Subjects underwent SMILE surgery on the VisuMax 800 platform. Preoperative offset coordinates (x, y) were measured; however, while preserving the directional sign, no kappa-angle-based laser centration compensation was applied intraoperatively, and the treatment center was set according to the system's default centration method. Except for the difference in compensation strategy, all other surgical procedures and postoperative management were identical to those in the compensation group.
Procedure: Apply no compensation to the Kappa angle
Subjects underwent SMILE surgery on the VisuMax 800 platform. Preoperative offset coordinates (x, y) were measured, and, while preserving the directional sign, a fixed intraoperative laser centration compensation of 0.1 mm was uniformly applied to all eligible study eyes to achieve a quantitative adjustment of the treatment center toward the visual axis. Except for the difference in compensation strategy, all other surgical procedures and postoperative management were identical to those in the non-compensation group.
Procedure: Apply compensation to the Kappa angle.
SMILE PRO is an upgraded version/procedural designation of SMILE (Small Incision Lenticule Extraction) performed on the ZEISS VisuMax 800 femtosecond laser platform and remains, in essence, an all-femtosecond corneal refractive procedure. Its basic principle is to use a femtosecond laser to create a lenticule within the corneal stroma together with a small incision, and then remove the lenticule through that incision, thereby reshaping the corneal curvature to correct myopia and astigmatism. In the compensation group, during preoperative parameter input, a fixed intraoperative laser centration compensation of 0.1 mm was uniformly applied to all study eyes meeting the inclusion criteria to achieve a quantitative adjustment of the treatment center toward the visual axis.
SMILE PRO is an upgraded version/procedural designation of SMILE (Small Incision Lenticule Extraction) performed on the ZEISS VisuMax 800 femtosecond laser platform and remains, in essence, an all-femtosecond corneal refractive procedure. Its basic principle is to use a femtosecond laser to create a lenticule within the corneal stroma together with a small incision, and then remove the lenticule through that incision, thereby reshaping the corneal curvature to correct myopia and astigmatism. In the non-compensation group, no kappa-angle-based laser centration compensation was applied intraoperatively, and the treatment center was set according to the system's default centration method.
Coma aberration
Coma aberration measured by wavefront aberrometry to evaluate the effect of intraoperative kappa-angle compensation on postoperative optical quality.
Time frame: 3 months after surgery
Higher-order aberrations
Total higher-order aberrations, spherical aberration, and trefoil aberration measured using wavefront aberrometry under standardized conditions to evaluate postoperative optical quality.
Time frame: 1 month, 3 months, and 6 months after surgery
Optical zone decentration
Decentration of the optical zone measured using corneal topography by determining the displacement between the optical zone center and the corneal vertex.
Time frame: 3 months after surgery
Visual acuity
Binocular uncorrected distance visual acuity and corrected distance visual acuity measured using standardized visual acuity charts to evaluate visual performance and safety.
Time frame: 1 month, 3 months, and 6 months after surgery
Manifest refraction
Postoperative sphere, cylinder, and spherical equivalent measured by manifest refraction.
Time frame: 1 month, 3 months, and 6 months after surgery
Refractive accuracy
Proportion of eyes within predefined ranges of target refraction to evaluate refractive predictability.
Time frame: 1 month, 3 months, and 6 months after surgery
Refractive stability
Refractive stability will be assessed as the change in manifest spherical equivalent refraction between postoperative visits.
Time frame: 1 month to 6 months after surgery
Contrast sensitivity
Contrast sensitivity will be measured using a standardized contrast sensitivity testing system (CSV-1000, VectorVision, USA) at multiple spatial frequencies.
Time frame: 3 months after surgery
Quality of Vision (QoV) score
Visual symptoms will be assessed using the Quality of Vision (QoV) questionnaire, which evaluates the frequency, severity, and bothersome nature of visual disturbances. Scores are recorded on ordinal scales, with higher scores indicating worse visual quality.
Time frame: 3 months after surgery
Patient satisfaction score
Patient satisfaction will be assessed using a 5-point rating scale. Scores range from 1 to 5, with higher scores indicating greater satisfaction.
Time frame: 3 months after surgery
Adverse events
Incidence of intraoperative or postoperative complications, including loss of corrected distance visual acuity and other clinically significant events.
Time frame: Up to 6 months after surgery
Plan to share: No
Started Apr 2026 (actual). Primary completion is estimated for May 2027, 13 months after the start.
Of 200 non-industry interventional studies with no phase under Myopia, half reached primary completion within 25 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 44. This study's planned 13 months is below that.
Counting every sponsor, half of 434 studies reached it within 14 months; a quarter within 3 and three quarters within 34.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
No contact was published for this record. The registry link below has the sponsor’s details.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Zhongshan Ophthalmic Center, Sun Yat-sen University →