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

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.

調査の概要

状態

まだ募集していません

条件

介入・治療

詳細な説明

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.

研究の種類

介入

入学 (推定)

52

段階

  • 適用できない

連絡先と場所

このセクションには、調査を実施する担当者の連絡先の詳細と、この調査が実施されている場所に関する情報が記載されています。

研究場所

    • Guangdong
      • Guangzhou、Guangdong、中国、510060
        • Zhongshan Ophthalmic Center

参加基準

研究者は、適格基準と呼ばれる特定の説明に適合する人を探します。これらの基準のいくつかの例は、人の一般的な健康状態または以前の治療です。

適格基準

就学可能な年齢

  • 大人

健康ボランティアの受け入れ

いいえ

説明

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.

研究計画

このセクションでは、研究がどのように設計され、研究が何を測定しているかなど、研究計画の詳細を提供します。

研究はどのように設計されていますか?

デザインの詳細

  • 主な目的:処理
  • 割り当て:ランダム化
  • 介入モデル:並列代入
  • マスキング:ダブル

武器と介入

参加者グループ / アーム
介入・治療
実験的: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.
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.
他の名前:
  • OcuLign-assisted cyclotorsion control
  • VISUMAX 800 OcuLign
アクティブコンパレータ: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.
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.

この研究は何を測定していますか?

主要な結果の測定

結果測定
メジャーの説明
時間枠
Residual refractive astigmatism
時間枠: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

二次結果の測定

結果測定
メジャーの説明
時間枠
Astigmatic correction predictability
時間枠: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
時間枠: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
時間枠: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
時間枠: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
時間枠: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
時間枠: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
時間枠: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
時間枠: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
時間枠: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
時間枠: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

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研究記録日

これらの日付は、ClinicalTrials.gov への研究記録と要約結果の提出の進捗状況を追跡します。研究記録と報告された結果は、国立医学図書館 (NLM) によって審査され、公開 Web サイトに掲載される前に、特定の品質管理基準を満たしていることが確認されます。

主要日程の研究

研究開始 (推定)

2026年7月13日

一次修了 (推定)

2027年6月30日

研究の完了 (推定)

2027年6月30日

試験登録日

最初に提出

2026年7月6日

QC基準を満たした最初の提出物

2026年7月6日

最初の投稿 (実際)

2026年7月10日

学習記録の更新

投稿された最後の更新 (実際)

2026年7月15日

QC基準を満たした最後の更新が送信されました

2026年7月13日

最終確認日

2026年7月1日

詳しくは

本研究に関する用語

追加の関連 MeSH 用語

その他の研究ID番号

  • IIT2026071

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いいえ

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