Comparison of Low- Versus High-Level Angle Kappa Compensation Strategies in SMILE Using the VisuMax 800: A Randomized Clinical Trial
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 入组人数
- 100
- 试验地点
- 1
- 主要终点
- Coma aberration
研究概览
简要总结
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
详细描述
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.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Double (Participant, Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 40 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age range: 18 - 40 years old. Patients with stable refractive status for >= 1 year, having myopia or myopic astigmatism, with refractive power within the range of SMILE procedure.
- •Normal corneal morphology and corneal thickness meeting the surgical requirements.
- •Best corrected visual acuity (CDVA) before surgery >= 1.
- •The kappa angle-related offset coordinates (x, y) obtained before surgery, with the absolute value of either |x| or |yl| of any eye >= 0.20mm.
- •Voluntary to undergo SMILE surgery on the VISUMAX800 platform, understanding the random grouping scheme and signing the informed consent form.
排除标准
- •History of prior ocular surgery, significant ocular trauma, or presence of corneal or ocular diseases that may affect the safety of refractive surgery.
- •Severe systemic diseases that may affect ocular healing or surgical safety.
- •Females who are pregnant or lactating.
- •Inability to cooperate as required to complete the procedure or follow-up visits.
研究组 & 干预措施
Low-Level compensation group
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.
干预措施: Apply low compensation to the Kappa angle. (Procedure)
High-Level compensation group
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.
干预措施: Apply high compensation to the Kappa angle. (Procedure)
结局指标
主要结局
Coma aberration
时间窗: 3 months after surgery
Coma aberration measured by wavefront aberrometry to evaluate the effect of intraoperative kappa-angle compensation on postoperative optical quality.
次要结局
- Higher-order aberrations(1 month, 3 months, and 6 months after surgery)
- Optical zone decentration(3 months after surgery)
- Visual Acuity(1 month, 3 months, and 6 months after surgery)
- Manifest refraction(1 month, 3 months, and 6 months after surgery)
- Refractive accuracy(1 month, 3 months, and 6 months after surgery)
- Refractive stability(1 month to 6 months after surgery)
- Contrast sensitivity(3 months after surgery)
- Quality of Vision (QoV) score(3 months after surgery)
- Patient satisfaction score(3 months after surgery)
- Adverse events(Up to 6 months after surgery)