Manually Performed Limbal Relaxing Incisions vs Femtosecond Laser-guided Astigmatic Keratotomy

Manually Performed Limbal Relaxing Incisions vs Femtosecond Laser-guided Astigmatic Keratotomy for Correction of Corneal Astigmatism After Phacoemulsification

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.

Study Overview

• Status: Completed
• Conditions: Corneal Astigmatism
• Intervention / Treatment: Procedure: limbal relaxing incisions; Procedure: astigmatic keratotomy

Detailed Description

Pre-operative evaluation:

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.

• Study Type: Interventional
• Enrollment (Actual): 90
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Assiut, Egypt, 71111
    • Faculty of Medicine, Assiut University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 17 years to 61 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. patients who have undergo phacoemulsification.
2. Clear cornea.
3. Astigmatism from 1 diopter up to 4 diopters

Exclusion Criteria:

1. corneal opacity.
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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: limbal relaxing incisions; Manually performed limbal relaxing incisions	Procedure: limbal relaxing incisions; Manually performed surgical procedure
Active Comparator: astigmatic keratotomy; femtosecond laser-guided astigmatic keratotomy	Procedure: astigmatic keratotomy; femtosecond laser guided surgical procedure

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Keratometric reading	measured by Corneal Tomography (Pentacam)	1 week

Collaborators and Investigators

• Sponsor: Assiut University

Study record dates

Study Major Dates

• Study Start (Actual): March 21, 2018
• Primary Completion (Actual): January 15, 2022
• Study Completion (Actual): January 15, 2022

Study Registration Dates

• First Submitted: August 24, 2017
• First Submitted That Met QC Criteria: August 25, 2017
• First Posted (Actual): August 29, 2017

Study Record Updates

• Last Update Posted (Actual): November 22, 2023
• Last Update Submitted That Met QC Criteria: November 18, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Astigmatism
• Other Study ID Numbers: 17200119

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: There is a possibility of using these data in another related study so i am not sure about the time of sharing the individual participant data

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No