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Comparison of Two Rotational Alignment Methods for Astigmatism Correction in SMILE Surgery

2026년 7월 13일 업데이트: Zhongshan Ophthalmic Center, Sun Yat-sen University

Comparison of Astigmatic Correction Outcomes Following SMILE With OcuLign-Assisted Cyclotorsion Control and Manual Limbal Marking: A Prospective Randomized Contralateral-Eye Noninferiority Study

Small incision lenticule extraction (SMILE) is a commonly used corneal refractive procedure for correcting myopia and myopic astigmatism. During astigmatism correction, eye rotation between the upright examination position and the supine surgical position may affect the alignment of the astigmatic treatment axis and may contribute to residual astigmatism after surgery.

Manual limbal marking is a commonly used method to guide cyclotorsion adjustment during refractive surgery. OcuLign is an assisted cyclotorsion control function of the VISUMAX 800 platform that helps identify ocular rotation and guide axis alignment during SMILE. However, direct clinical evidence comparing OcuLign-assisted cyclotorsion control with manual limbal marking during SMILE is limited.

This study is a single-center, prospective, randomized, masked, contralateral-eye non-inferiority trial. Adults aged 18 to 40 years with stable myopia and astigmatism who plan to undergo bilateral SMILE surgery will be enrolled. In each participant, one eye will receive SMILE with OcuLign-assisted cyclotorsion control, and the fellow eye will receive SMILE with manual limbal marking-guided cyclotorsion adjustment. The treatment assigned to the right eye will be determined by randomization.

The primary objective is to compare residual refractive astigmatism at 3 months after surgery between the two methods. Secondary outcomes include visual acuity, refractive predictability and stability, astigmatism vector analysis, higher-order aberrations, contrast sensitivity, patient-reported quality of vision, overall satisfaction, and safety outcomes. Participants will be followed for approximately 6 months after surgery.

연구 개요

상태

아직 모집하지 않음

정황

개입 / 치료

상세 설명

Accurate alignment of the astigmatic treatment axis is an important factor in the correction of myopic astigmatism during small incision lenticule extraction (SMILE). Cyclotorsion may occur when a patient changes from the upright preoperative examination position to the supine surgical position, and may also be influenced by fixation, head position, and suction during surgery. Inadequate compensation for ocular rotation may reduce astigmatic correction accuracy and contribute to postoperative residual astigmatism.

Manual limbal marking is a commonly used method for cyclotorsion adjustment in corneal refractive surgery. This method is clinically feasible and widely used, but it depends on preoperative marking and intraoperative manual judgment. Marking clarity, ocular surface conditions, patient cooperation, and surgeon experience may affect the accuracy and reproducibility of the adjustment. OcuLign is an assisted cyclotorsion control function of the VISUMAX 800 platform that helps identify ocular rotation and guide axis alignment during SMILE. This study is designed to compare OcuLign-assisted cyclotorsion control with manual limbal marking-guided cyclotorsion adjustment during SMILE.

This trial uses a prospective, randomized, contralateral-eye non-inferiority design. Each participant will undergo bilateral SMILE surgery. One eye will be assigned to OcuLign-assisted cyclotorsion control, and the fellow eye will be assigned to manual limbal marking-guided cyclotorsion adjustment, according to a prespecified randomization sequence. This paired-eye design is intended to reduce inter-individual variability in refractive characteristics, healing response, and subjective visual perception. Apart from the method of cyclotorsion adjustment, surgical parameters, lenticule design, suction procedure, postoperative medication, and follow-up schedule will be kept consistent between the two eyes.

Participants and postoperative outcome assessors will be masked to the eye-level treatment assignment whenever feasible. The operating surgeon cannot be masked because the assigned cyclotorsion adjustment method must be performed during surgery. Postoperative assessments will be conducted at predefined follow-up visits through approximately 6 months after surgery.

The primary comparison will evaluate whether OcuLign-assisted cyclotorsion control is non-inferior to manual limbal marking-guided adjustment in terms of residual refractive astigmatism at 3 months after surgery. Secondary assessments will evaluate visual acuity, refractive predictability and stability, astigmatism vector parameters, higher-order aberrations, contrast sensitivity, patient-reported quality of vision, satisfaction, and safety. Safety monitoring will include loss of corrected distance visual acuity and postoperative adverse events.

연구 유형

중재적

등록 (추정된)

52

단계

  • 해당 없음

연락처 및 위치

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연구 장소

  • 중국
    • Guangdong
      • Guangzhou, Guangdong, 중국, 510060
        • Zhongshan Ophthalmic Center

참여기준

연구원은 적격성 기준이라는 특정 설명에 맞는 사람을 찾습니다. 이러한 기준의 몇 가지 예는 개인의 일반적인 건강 상태 또는 이전 치료입니다.

자격 기준

공부할 수 있는 나이

  • 성인

건강한 자원 봉사자를 받아들입니다

아니

설명

Inclusion Criteria:

  1. Age range: 18 - 40 years old. Patients with myopic astigmatism and stable refractive status for >= 1 year.
  2. Normal corneal morphology in both eyes, with corneal thickness and other ocular parameters meeting the requirements for SMILE surgery.
  3. Preoperative corrected distance visual acuity (CDVA) >= 1.0 in both eyes.
  4. Manifest refractive cylinder >= 0.75 D in both eyes, with an interocular difference in absolute cylinder power <= 1.00 D.
  5. Both eyes can provide reliable preoperative upright-position image information required for astigmatic axis recognition, and are judged by the investigator to meet the requirements for OcuLign cyclotorsion recognition and axis alignment on the VISUMAX 800 platform.
  6. Voluntary to undergo bilateral SMILE surgery on the VISUMAX 800 platform, understanding the random eye-assignment scheme and signing the informed consent form.

Exclusion Criteria:

  1. History of prior ocular surgery, significant ocular trauma, or presence of ocular diseases that may affect the safety of refractive surgery or the interpretation of study outcomes.
  2. Irregular astigmatism or poor repeatability of bilateral astigmatism measurements, making reliable astigmatic axis analysis impossible.
  3. Presence of strabismus, nystagmus, significant binocular vision abnormality, or any condition that may affect fixation or cooperation during examinations.
  4. Severe systemic diseases that may affect ocular healing or surgical safety.
  5. Females who are pregnant or lactating.
  6. Inability to complete the required postoperative follow-up visits or questionnaire assessments.

공부 계획

이 섹션에서는 연구 설계 방법과 연구가 측정하는 내용을 포함하여 연구 계획에 대한 세부 정보를 제공합니다.

연구는 어떻게 설계됩니까?

디자인 세부사항

  • 주 목적: 치료
  • 할당: 무작위
  • 중재 모델: 병렬 할당
  • 마스킹: 더블

무기와 개입

참가자 그룹 / 팔
개입 / 치료
실험적: OcuLign-Assisted Cyclotorsion Control
One eye of each participant will undergo SMILE using OcuLign-assisted cyclotorsion control on the VISUMAX 800 platform. OcuLign will be used intraoperatively to assist in identifying ocular rotation and guiding astigmatic axis alignment. Apart from the cyclotorsion adjustment method, the surgical parameters, lenticule design, suction procedure, postoperative medication, and follow-up schedule will be the same as those used for the fellow eye.
절차: Device-assisted cyclotorsion control during SMILE
One eye of each participant will undergo SMILE using device-assisted cyclotorsion control with the OcuLign function of the VISUMAX 800 platform. During surgery, OcuLign will assist in identifying ocular rotation and guiding astigmatic axis alignment. Apart from the cyclotorsion adjustment method, the surgical parameters, lenticule design, suction procedure, postoperative medication, and follow-up schedule will be the same as those used for the fellow eye.
다른 이름들:
  • OcuLign-assisted cyclotorsion control
  • VISUMAX 800 OcuLign
활성 비교기: Manual Limbal Marking-Guided Adjustment
The fellow eye of each participant will undergo SMILE using manual limbal marking-guided cyclotorsion adjustment. Limbal reference marks will be made in the upright preoperative position, and intraoperative axis alignment will be manually adjusted according to the marks and the surgical reference direction. Apart from the cyclotorsion adjustment method, the surgical parameters, surgical procedure, postoperative medication, and follow-up schedule will be the same as those used for the contralateral eye.
절차: Manual limbal marking-guided cyclotorsion adjustment during SMILE
The fellow eye of each participant will undergo SMILE using manual limbal marking-guided cyclotorsion adjustment. Limbal reference marks will be made in the upright preoperative position, and intraoperative axis alignment will be manually adjusted according to the limbal marks and the surgical reference direction. Apart from the cyclotorsion adjustment method, the surgical parameters, surgical procedure, postoperative medication, and follow-up schedule will be the same as those used for the contralateral eye.

연구는 무엇을 측정합니까?

주요 결과 측정

결과 측정
측정값 설명
기간
Residual refractive astigmatism
기간: 3 months after surgery
Residual refractive astigmatism will be measured as the absolute manifest cylinder power in diopters at 3 months after SMILE. The primary analysis will compare residual refractive astigmatism between eyes treated with OcuLign-assisted cyclotorsion control and eyes treated with manual limbal marking-guided cyclotorsion adjustment to evaluate non-inferiority.
3 months after surgery

2차 결과 측정

결과 측정
측정값 설명
기간
Astigmatic correction predictability
기간: 1 month, 3 months, and 6 months after surgery
Astigmatic correction predictability will be assessed as the proportion of eyes with postoperative residual manifest cylinder within predefined thresholds, including ≤0.25 D, ≤0.50 D, and ≤1.00 D.
1 month, 3 months, and 6 months after surgery
Visual acuity
기간: 1 month, 3 months, and 6 months after surgery
Uncorrected distance visual acuity and corrected distance visual acuity will be measured using standardized visual acuity charts and recorded as logMAR visual acuity. Visual acuity-derived performance will also be summarized using the safety index and efficacy index, calculated from the same visual acuity measurements. The safety index is defined as postoperative corrected distance visual acuity divided by preoperative corrected distance visual acuity, and the efficacy index is defined as postoperative uncorrected distance visual acuity divided by preoperative corrected distance visual acuity.
1 month, 3 months, and 6 months after surgery
Manifest refraction
기간: 1 month, 3 months, and 6 months after surgery
Postoperative manifest refraction will include sphere, cylinder, and spherical equivalent measured by standard manifest refraction.
1 month, 3 months, and 6 months after surgery
Refractive accuracy
기간: 1 month, 3 months, and 6 months after surgery
Refractive accuracy will be assessed as the proportion of eyes with postoperative spherical equivalent within predefined ranges of the target refraction, including within ±0.25 D, ±0.50 D, and ±1.00 D.
1 month, 3 months, and 6 months after surgery
Refractive stability
기간: 1 month to 6 months after surgery
Refractive stability will be assessed as the change in manifest spherical equivalent refraction between postoperative follow-up visits.
1 month to 6 months after surgery
Contrast sensitivity
기간: 3 months after surgery
Contrast sensitivity will be measured under standardized conditions using the CSV-1000 contrast sensitivity testing system at multiple spatial frequencies, including 3, 6, 12, and 18 cycles per degree. The area under the log contrast sensitivity function may be calculated as a summary measure when appropriate.
3 months after surgery
Quality of Vision score
기간: 3 months after surgery
Subjective visual symptoms will be assessed using the Quality of Vision questionnaire, which evaluates the frequency, severity, and bothersome nature of visual disturbances such as glare, halos, and double vision. Higher scores indicate worse subjective visual quality.
3 months after surgery
Overall visual satisfaction score
기간: 3 months after surgery
Overall visual satisfaction will be assessed using a 5-point Likert rating scale. Scores range from 1 to 5, with higher scores indicating greater satisfaction.
3 months after surgery
Astigmatic Correction Assessed by Alpins Vector Analysis
기간: 3 months after surgery
Postoperative astigmatic correction will be assessed using the Alpins vector analysis method based on refractive cylinder and axis data. This outcome will be used to describe the overall accuracy of astigmatism correction after surgery.
3 months after surgery
Higher-Order Wavefront Aberration Assessment
기간: 1 month, 3 months, and 6 months after surgery
Higher-order wavefront aberrations will be measured using wavefront aberrometry under standardized conditions to assess postoperative optical quality.
1 month, 3 months, and 6 months after surgery

공동 작업자 및 조사자

여기에서 이 연구와 관련된 사람과 조직을 찾을 수 있습니다.

스폰서

Zhongshan Ophthalmic Center, Sun Yat-sen University

간행물 및 유용한 링크

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일반 간행물

연구 기록 날짜

이 날짜는 ClinicalTrials.gov에 대한 연구 기록 및 요약 결과 제출의 진행 상황을 추적합니다. 연구 기록 및 보고된 결과는 공개 웹사이트에 게시되기 전에 특정 품질 관리 기준을 충족하는지 확인하기 위해 국립 의학 도서관(NLM)에서 검토합니다.

연구 주요 날짜

연구 시작 (추정된)

2026년 7월 13일

기본 완료 (추정된)

2027년 6월 30일

연구 완료 (추정된)

2027년 6월 30일

연구 등록 날짜

최초 제출

2026년 7월 6일

QC 기준을 충족하는 최초 제출

2026년 7월 6일

처음 게시됨 (실제)

2026년 7월 10일

연구 기록 업데이트

마지막 업데이트 게시됨 (실제)

2026년 7월 15일

QC 기준을 충족하는 마지막 업데이트 제출

2026년 7월 13일

마지막으로 확인됨

2026년 7월 1일

추가 정보

이 연구와 관련된 용어

키워드

추가 관련 MeSH 약관

기타 연구 ID 번호

  • IIT2026071

개별 참가자 데이터(IPD) 계획

개별 참가자 데이터(IPD)를 공유할 계획입니까?

아니요

약물 및 장치 정보, 연구 문서

미국 FDA 규제 의약품 연구

아니

미국 FDA 규제 기기 제품 연구

아니

이 정보는 변경 없이 clinicaltrials.gov 웹사이트에서 직접 가져온 것입니다. 귀하의 연구 세부 정보를 변경, 제거 또는 업데이트하도록 요청하는 경우 register@clinicaltrials.gov. 문의하십시오. 변경 사항이 clinicaltrials.gov에 구현되는 즉시 저희 웹사이트에도 자동으로 업데이트됩니다. .

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