Manually Performed Limbal Relaxing Incisions vs Femtosecond Laser-guided Astigmatic Keratotomy
NCT ID: NCT03264534
Last Updated: 2023-11-22
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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COMPLETED
NA
90 participants
INTERVENTIONAL
2018-03-21
2022-01-15
Brief Summary
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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.
Detailed Description
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1. Close examination of the peripheral cornea by slit lamb, particularly in the areas where the incisions will be placed.
2. Fundus examination to exclude other causes of diminution of vision.
3. IOP measure.
4. Precise manifest refraction, uncorrected visual acuity and best corrected visual acuity by snellen's chart.
5. Standard keratometry to confirm diopters of corneal astigmatism.
6. 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.
Conditions
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Study Design
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RANDOMIZED
PARALLEL
TREATMENT
NONE
Study Groups
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limbal relaxing incisions
Manually performed limbal relaxing incisions
limbal relaxing incisions
Manually performed surgical procedure
astigmatic keratotomy
femtosecond laser-guided astigmatic keratotomy
astigmatic keratotomy
femtosecond laser guided surgical procedure
Interventions
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limbal relaxing incisions
Manually performed surgical procedure
astigmatic keratotomy
femtosecond laser guided surgical procedure
Eligibility Criteria
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Inclusion Criteria
2. Clear cornea.
3. Astigmatism from 1 diopter up to 4 diopters
Exclusion Criteria
2. History of corneal surgery.
3. Thin cornea.
4. Other cause of diminution of vision rather than corneal astigmatism (eg: optic disc atrophy \& maculopathy).
5. Astigmatism less than 1 diopter and more than 4 diopters.
21 Years
65 Years
ALL
No
Sponsors
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Assiut University
OTHER
Responsible Party
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Ashraf Rashwan
Principal Investigator
Locations
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Faculty of Medicine, Assiut University
Asyut, , Egypt
Countries
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Other Identifiers
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17200119
Identifier Type: -
Identifier Source: org_study_id