Manually Performed Limbal Relaxing Incisions vs Femtosecond Laser-guided Astigmatic Keratotomy for Correction of Corneal Astigmatism After Phacoemulsification
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 90
- 试验地点
- 2
- 主要终点
- Keratometric reading
研究概览
简要总结
Astigmatic keratotomy (AK) is used to treat numerous refractive disorders, including congenital astigmatism, residual corneal astigmatism at the time of or following cataract surgery, post-traumatic astigmatism, and astigmatism after corneal transplantation.
Within the past few years, much consideration has been given to an evolutionary variant of the procedure, the limbal relaxing incision (LRI). By moving the incision farther to the periphery, cataract surgeons can safely and predictably remediate mild to moderate amounts of regular astigmatism at the time of cataract surgery by performing this incisional technique.
Recent technological developments have shifted ophthalmologist's attention from manually created LRIs and astigmatic keratotomy procedures to femtosecond laser-guided procedures. Femtosecond lasers offer superior incisional accuracy and reproducibility coupled with minimal effects on collateral tissues, achieving levels of safety and reproducibility exceeding those of mechanical techniques. A major clinical application of the femtosecond laser is for creating arcuate incisions that have a precise and accurate length, depth, angular position, and optical zone.
详细描述
Pre-operative evaluation:
- Close examination of the peripheral cornea by slit lamb, particularly in the areas where the incisions will be placed.
- Fundus examination to exclude other causes of diminution of vision.
- IOP measure.
- Precise manifest refraction, uncorrected visual acuity and best corrected visual acuity by snellen's chart.
- Standard keratometry to confirm diopters of corneal astigmatism.
- Corneal Tomography (Pentacam).
Surgical procedures:
LRIs are performed using topical anesthesia. Patients are instructed to fixate on the microscope light. Before surgery, the steep meridian was identified with a marker dyed with methylene blue with the patient sitting up right. A diamond knife is set at a depth of 0.600 mm to 0.650 mm based on the peripheral pachymetric readings over the area of intended incision. The goal was a maximum reduction in astigmatism without overcorrection in with-the rule cases and with little overcorrection in against the rule cases. In the case of an overcorrection, the LRI can be sutured without creating any irregular astigmatism.
Performing femtosecond laser-guided astigmatic keratotomy requires the parameters of length, position, depth and distance from the visual axis where the incisions will be created. The depth of our incisions is 85% of the corneal pachymetry in the area of the incision. We have set our distance from the visual axis at 8 mm. This information is all downloaded onto the femtosecond laser. Then, we begin the surgical procedure by docking the laser onto the cornea. An overlay of the incisions is then visible on the surgical screen. After treatment, we bring the patient to the operating microscope and open the incisions with a Sinskey hook. By using low energy, the incisions do not have significant effect until they are opened.
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
- None
入排标准
- 年龄范围
- 21 Years 至 65 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •patients who have undergo phacoemulsification.
- •Clear cornea.
- •Astigmatism from 1 diopter up to 4 diopters
排除标准
- •corneal opacity.
- •History of corneal surgery.
- •Thin cornea.
- •Other cause of diminution of vision rather than corneal astigmatism (eg: optic disc atrophy & maculopathy).
- •Astigmatism less than 1 diopter and more than 4 diopters.
结局指标
主要结局
Keratometric reading
时间窗: 1 week
measured by Corneal Tomography (Pentacam)
次要结局
未报告次要终点
研究者
Ashraf Rashwan
Principal Investigator
Assiut University