Q Value Customized Versus Wavefront Optimized Ablation in Femtosecond Laser-Assisted LASIK for Myopia and Myopic Astigmatism. A Contralateral Comparative Study
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 40
- 试验地点
- 1
- 主要终点
- Postoperative Q value
研究概览
简要总结
Corneal asphericity is expressed numerically as the "Q-value". A minus value means that corneal curvature flattens towards the periphery and the cornea is prolate in shape, but when the curvature steepens towards the periphery, the cornea is oblate in shape and has a positive Q-value.
The current study evaluates the effect of LASIK eye surgery on corneal asphericity by comparing 2 software treatment platforms; the Q value customized ablation versus the conventional Wave-front optimized ablation in a fellow eye study pattern.
详细描述
The standard excimer laser correction of myopia is associated with decreased visual quality in the form of a decrease in contrast sensitivity and night vision. This degradation of the visual quality is attributed to changes in the corneal asphericity that increase the high order aberrations (HOAs), such as spherical aberrations because it leads to shifting of the corneal asphericity towards the oblate shape.
The wavefront-optimized (WFO) profile avoids the creation of new HOAs, but it is not able to treat those which are already present pre-operatively.
The Q-adjusted treatments correct the sphero-cylindrical refractive errors and try to maintain the corneal asphericity at the same time, but like the WFO ablation profiles, it is limited to correcting the spherical aberrations and not the non-rotational symmetric HOAs.
Some studies compared Lasers of two different platforms on contralateral eyes of the same patient in order to minimize inter-patient differences such as corneal wound healing and corneal biomechanics. By exclusion of these inter-patient differences, a more accurate judgment on the outcomes can be achieved.
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Single (Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Candidates for Laser vision correction (LVC) with
- •Myopic Spherical Equivalent up to -12 diopters.
- •Myopic astigmatism up to -6 diopters.
- •Corneal thinnest location ≥ 500 um 4- Residual stromal bed ≥ 300 um.
排除标准
- •Patients not candidates for LVC.
- •Hyperopic patients or mixed astigmatism.
- •Systemic disease that contraindicates LVC.
- •Intra- or post-operative complications. 5- Previous corneal surgery
研究组 & 干预措施
Custom Q treatment group
For every patient, the eye with the greater myopic spherical equivalent (SE) will be assigned for the Custom-Q treatment group.
干预措施: Femtosecond laser assisted LASIK eye surgery (Procedure)
Wave-front optimized (WFO) group
For every patient, the other eye with the lesser myopic SE will be assigned for the WFO treatment group
干预措施: Femtosecond laser assisted LASIK eye surgery (Procedure)
结局指标
主要结局
Postoperative Q value
时间窗: 6 months
Pentacam evaluation of post-LASIK Q value
次要结局
- Postoperative corneal thickness at the pupillary center(6 months)
研究者
Mahmoud Abdel-Radi
Principal Investigator
Assiut University