Evaluation of Different Lenticule Diameters in Myopic Astigmatism Correction With SMILE Procedures

September 25, 2023 updated by: Al Watany Eye Hospital

Small incision lenticule extraction (SMILE) is a refractive intrastromal procedure for myopia and myopic astigmatism correction. Most of the studies evaluating astigmatic correction by SMILE reported astigmatic under-correction, especially in high degrees of astigmatism.

This under-correction could be due to: first, the active eye tracker or the iris registration is not yet available to overcome the cyclotorsion that occurred during the treatment with the VisuMax femtosecond laser system (Carl Zeiss Meditec, Jena, Germany) which could be overcome by manual compensation technique, especially in higher degrees of cylinders (> 1.5 diopters (D)). Second, in patients with small lenticule diameters, the more abrupt change in thickness at the edge of the treated area could induce more stromal and epithelial healing in this area. Thus, the astigmatic correction would be less effective with small than large lenticule diameters for similar high preoperative astigmatism.

This study assessed the outcome of using a 0.5 millimeter (mm) larger lenticule diameter in the fellow eyes of myopic astigmatic correction SMILE participants. This assessment included the safety and effectiveness indices, the refractive and visual outcomes, the contrast sensitivity, and some morphological outcomes such as corneal curvature and epithelial and corneal thickness.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Detailed Description

Study Title: Evaluation of different lenticule diameters in myopic astigmatic correction with SMILE procedures Primary Investigator: Dr. Ahmed Sedky (Eye Subspecialty Center, Cairo, Egypt, 18 Elkhalifa Elmamoun Street, Heliopolis, Cairo, Egypt) Co-Investigators: Sherine S Wahba, Maged M Roshdy, Nermeen A Refaat Study Objectives Primary Objective: To study the effect of changing the lenticule diameter on the safety and effectiveness of myopic astigmatism correction with the SMILE procedure.

Secondary Objective: To compare other outcomes such as visual outcomes including immediate visual acuity, contrast sensitivity, and epithelial remodeling.

Participants and Methods:

Study Setting: Eye Subspecialty Center, Cairo, Egypt, 18 Elkhalifa Elmamoun Street, Heliopolis, Cairo, Egypt and Al Watany Eye Hospital, Althawra Street, Cairo, Egypt Study design: Hospital-based, comparative, prospective, interventional contralateral eye study Sample size and randomization: 50 participants fulfilling the inclusion criteria will be enrolled in the study. Their right eyes undergo SMILE procedure using the standard 6.5 mm lenticule diameter and their left eyes undergo SMILE procedure but using a larger lenticule diameter of 7.0 mm.

Ethical issues:

Institutional ethics committee approval will be obtained. Participants' informed consent will be taken and the procedure explained to them in their own language. Any intra-operative or post-operative complications occurring in either group will be documented and duly informed to the ethics committee

Preoperative evaluation:

  1. Anterior and posterior segment clinical examination
  2. Uncorrected distance visual acuity (UDVA) in decimal and logMAR units
  3. Corrected distance visual acuity (CDVA) in decimal and logMAR units
  4. Corneal tomography using the Pentacam high resolution (HR) (Oculus Optikgeräte, Wetzlar, Germany) including the flattest and steepest meridians (in keratometric diopters (D), the axes (in degrees)
  5. Contrast sensitivity (CSV1000E test (Good-Lite, Elgin, Illinois, USA)) in 4 different special frequencies
  6. Anterior segment Optical Coherence Tomography (Cirrus, Carl Zeiss Meditec, Jena, Germany) measurement of total corneal and epithelial thickness in µm Study duration: 3 months for recruitment of the patients.

Surgical technique:

All surgeries will be performed under topical anesthesia using the VisuMax femtosecond laser with the following parameters:

Cap thickness of 120 μm Cap diameter is either 7.5 mm for lenticule diameter 6.5 mm or 8.0 mm for lenticule diameter 7.0 mm.

Cap side cut angle 70° 3 mm incision positioned at 100° and angled at 45° A transition zone of 0.1 mm and clearance of 0.5 mm Lenticule side cut angle of 90° and edge lenticule thickness of 15 μm Directly preoperative, the limbus will be marked in the 0° to 180° axis with a marker pen in the upright head position on the slit lamp. Then, the patient will be positioned under the VisuMax femtosecond laser and instructed to look into the green flashing fixation light. Once proper centration is achieved, the eye will be docked to the patient interface and suction will be applied.

Manual compensation will be done by gently rotating the contact glass to align the horizontal marks on the eye to the 0° to 180° axis. Once both are aligned, the laser process will be done to create the refractive lenticule followed by its dissection and washing of the interface by a balanced salt solution.

Medication: will be the standard treatment; topical steroids and antibiotics 4 times per day for 10 days and tear substitutes 4 times daily for one to two months.

Postoperative evaluation:

Follow-up of the subjects will be done in 1 day, 1 week, 3 months, and 6 months.

Data will be collected for analysis starting from 1 week, including:

  1. Uncorrected distance visual acuity (UDVA) in decimal and logMAR units
  2. Corrected distance visual acuity (CDVA) in decimal and logMAR units
  3. Corneal tomography using the Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) including the flattest and steepest meridians (in diopters (D), the axes (in degree)
  4. Contrast sensitivity (CSV1000E test (Good-Lite, Elgin, IL, USA)) in 4 different special frequencies
  5. Anterior segment Optical Coherence Tomography (Cirrus HD-OCT, Carl Zeiss Meditec, Jena, Germany) measurement of total corneal and epithelial thickness in µm.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
50

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Egypt
      • Cairo, Egypt, 11775
        • Recruiting
        • Al Watany Eye Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age groups between 18 and 50 years
  • Myopic astigmatism with up to -10.00 D spherical equivalent (SE) and a minimum astigmatism of -1.0 D and a maximum of -5 D. The astigmatism will be divided into low astigmatism (<0.75 D), moderate astigmatism (1.5- 3 D) and high astigmatism (>3 D).
  • Corrected distance visual acuity (CDVA) of 0.7 or better (decimal)

Exclusion Criteria:

  • Thin corneas (< 490 μm)
  • Proven or suspicious cases of corneal ectatic conditions by corneal tomography
  • Previous ocular surgeries
  • Patients taking systemic steroids, immunosuppressants, oral contraceptives, or antidepressants
  • Pregnant females
  • Corneal scars or any ocular pathology likely to affect visual outcomes

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Control
group A, SMILE procedure with lenticule diameter of 6.5 mm
Procedure: Small Incision Lenticule Extraction (SMILE)

All surgeries will be performed under topical anesthesia using the VisuMax femtosecond laser with the following parameters:

  • Cap thickness of 120 μm
  • Cap diameter of 1 mm larger than the lenticule diameter
  • Cap side cut angle 70°
  • 3 mm incision positioned at 100° and angled at 45°
  • Transition zone of 0.1 mm and clearance of 0.5 mm
  • Lenticule side cut angle of 90° and edge lenticule thickness of 15 μm
Active Comparator: Study cases
group B, SMILE procedure with lenticule diameter of 7.0 mm
Procedure: Small Incision Lenticule Extraction (SMILE)

All surgeries will be performed under topical anesthesia using the VisuMax femtosecond laser with the following parameters:

  • Cap thickness of 120 μm
  • Cap diameter of 1 mm larger than the lenticule diameter
  • Cap side cut angle 70°
  • 3 mm incision positioned at 100° and angled at 45°
  • Transition zone of 0.1 mm and clearance of 0.5 mm
  • Lenticule side cut angle of 90° and edge lenticule thickness of 15 μm

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
The safety index of using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism
Time Frame: up to 6 months
The safety index (unitless parameter) is calculated as postoperative CDVA/ preoperative CDVA (both in decimal units).
up to 6 months
The efficacy index of using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism
Time Frame: up to 6 months
The efficacy index (unitless parameter) is calculated as postoperative UDVA/ preoperative CDVA (both in decimal units).
up to 6 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Refractive outcomes of using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
Time Frame: up to 6 months
To compare subjective refractive outcomes including spherical equivalent and residual astigmatism (in diopters) of SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
up to 6 months
Visual acuity outcomes of using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
Time Frame: up to 6 months
To compare postoperative UDVA and CDVA (in logMAR) of SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
up to 6 months
Contrast sensitivity outcomes of using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
Time Frame: up to 6 months
To compare postoperative photopic and mesopic contrast sensitivity (in log unit) at 3, 6, 12, and 18 cycles per degree of SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism. This will be done using the CSV1000E device (Good-Lite, Elgin, IL, USA)
up to 6 months
Corneal curvature changes after SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
Time Frame: up to 6 months
To compare postoperative corneal curvature in flattest and steepest meridia (in keratometric diopters) after SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism. This will be done using the Pentacam high resolution (HR) (Oculus Optikgeräte, Wetzlar, Germany).
up to 6 months
Corneal structural changes after SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism.
Time Frame: up to 6 months
To compare postoperative and central corneal and epithelial thickness (in micrometers) and standard deviation of epithelial thickness in different locations (in micrometers) after SMILE procedure using 7 and 6.5 mm lenticule diameters SMILE to treat myopic astigmatism. This will be done using the anterior segment OCT (Cirrus HD-OCT, Carl Zeiss Meditec, Jena, Germany)
up to 6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Al Watany Eye Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

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Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 27, 2018

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 28, 2024

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 30, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 12, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 25, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 2, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 2, 2023

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 25, 2023

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • REF-2018-003

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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