An interventional study of Apply high compensation to the Kappa angle. and Apply low 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
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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 13th 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.
1,159 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 100 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 compare two intraoperative kappa-angle compensation strategies during small incision lenticule extraction (SMILE) using the VisuMax 800 platform in patients with relatively large kappa-angle offsets.
Angle kappa represents the difference between the visual axis and the pupil center. In patients with a large offset, pupil-centered treatment may lead to decentration of the optical zone, which can induce higher-order aberrations and affect postoperative visual quality. The VisuMax 800 system allows intraoperative adjustment of the treatment center based on the measured offset, making different compensation strategies possible.
The main questions this study aims to answer are:
Does low kappa-angle compensation (50%) result in lower postoperative higher-order aberrations than high compensation (100%)? Does the compensation strategy influence visual acuity, refractive outcomes, contrast sensitivity, and subjective visual quality after SMILE? Are the measurements obtained from different diagnostic devices consistent when evaluating kappa-related parameters?
Researchers will compare SMILE with low compensation to SMILE with high compensation to determine which strategy provides better optical quality and visual performance.
Participants will:
Undergo SMILE surgery using either low or high kappa-angle compensation Complete scheduled postoperative examinations at 1 month, 3 months, and 6 months Receive measurements of visual acuity, refraction, higher-order aberrations, contrast sensitivity, and patient-reported visual outcomes Be monitored for safety outcomes and adverse events during follow-up
Angle kappa refers to the offset between the visual axis and the pupil center and is an important factor influencing the centration of the treatment zone during corneal refractive surgery. In patients with relatively large offsets, pupil-centered treatment may lead to decentered lenticule extraction, which can induce higher-order aberrations, especially coma, and may reduce postoperative visual quality.
Small incision lenticule extraction (SMILE) is a widely used corneal refractive procedure with good safety and predictability. The new-generation VisuMax 800 femtosecond laser system incorporates machine vision-assisted alignment, allowing the surgeon to adjust the treatment center according to the measured displacement between the corneal vertex and the pupil center. This enables intraoperative compensation based on the kappa-angle offset.
Previous studies in excimer laser surgery have evaluated different proportions of kappa-angle compensation, but prospective randomized studies in SMILE are limited, particularly in patients with relatively large offsets. In addition, the optimal amount of compensation during SMILE has not been clearly determined.
This study is a single-center, randomized, parallel-group clinical trial designed to compare two predefined compensation strategies during SMILE using the VisuMax 800 platform. Patients aged 18-40 years with stable myopia or myopic astigmatism and a kappa-related displacement of at least 0.20 mm will be enrolled and randomly assigned to one of two groups.
Participants in the low-compensation group will undergo SMILE with the treatment center shifted by 50% of the measured offset coordinates, while participants in the high-compensation group will undergo SMILE with 100% compensation of the measured offset. All surgeries will be performed using the same surgical protocol, and postoperative management will be identical in both groups.
Participants will undergo routine ophthalmic examinations before surgery and at scheduled follow-up visits after surgery. The primary evaluation will assess postoperative higher-order aberrations at 3 months. Secondary evaluations will include visual acuity, refractive outcomes, refractive stability, contrast sensitivity, patient-reported visual quality, optical zone centration, and safety outcomes. In addition, measurements obtained from different diagnostic devices will be compared to assess consistency.
The results of this study will help determine the optimal intraoperative compensation strategy for SMILE in patients with large kappa-angle offsets and may contribute to improving postoperative visual quality and refractive accuracy.
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. Preoperatively, decentration coordinates (x, y) were measured. While preserving the directional sign, the absolute value of the planned compensation was set to 50% of the measured decentration; the values were then rounded to the nearest increment permitted by the device input precision and entered into the system. All other surgical procedures, as well as postoperative medication and follow-up protocols, were performed according to a standardized regimen.
Procedure: Apply low compensation to the Kappa angle.
Subjects also underwent SMILE surgery on the VisuMax 800 platform. Decentration coordinates (x, y) were measured, and the theoretical compensation was set at 100% of the measured decentration. While preserving the directional sign, the measured values were entered directly into the device without any additional adjustment. Except for the different compensation strategy, all other surgical procedures and postoperative management were identical to those of the low-compensation group.
Procedure: Apply high 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. It 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 high-level compensation group, a high level of compensation for the kappa angle was applied during the preoperative parameter input.
SMILE PRO is an upgraded version/procedural designation of SMILE (Small Incision Lenticule Extraction) performed on the ZEISS VisuMax 800 femtosecond laser platform. It is essentially an all-femtosecond corneal refractive procedure. Its basic principle is to use a femtosecond laser to create a lenticule within the corneal stroma and a small incision, and then remove the lenticule through the incision, thereby reshaping the corneal curvature to correct myopia and astigmatism. In the low-level compensation group, a low level of kappa-angle compensation was applied during the preoperative parameter input.
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.
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Zhongshan Ophthalmic Center, Sun Yat-sen University →