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Assessment of Corneal Stiffness in Keratoconus After Crosslinking by Corvis ST and OCT.

Primary Purpose

Keratoconus

Status
Not yet recruiting
Phase
Not Applicable
Locations
Study Type
Interventional
Intervention
Corvis ST (dynamic Scheimpflug technology)
Sponsored by
Cairo University
About
Eligibility
Locations
Outcomes
Full info

About this trial

This is an interventional diagnostic trial for Keratoconus

Eligibility Criteria

18 Years - 40 Years (Adult)All SexesAccepts Healthy Volunteers

Inclusion Criteria:

  • Patients with documented progressive keratoconus within one year include any of the following:

A. ≥ 1.00 diopter increase in maximal keratometry (Kmax). B. ≥ 1.00 diopter increase in the manifest cylinder. C. ≥ 0.75 diopter increase in average of Kmax and Kmin (Kmean). D. ≥ 2% decrease in central thickness. E. ≥ 1.50 diopter increase in the central K power from baseline. F. ≥ 1.0 diopter increase in manifest spherical equivalent change (MRSE).

  • All patients have minimal corneal stromal thickness 400 μm before UVA irradiation.

Exclusion Criteria:

  • Patients with corneal rings.
  • Advanced keratoconus with corneal scarring.
  • History of herpetic keratitis and severe corneal infection.
  • Pregnancy or breastfeeding.
  • The use of rigid contact lens¬es for more than 4 weeks before the baseline evaluation.

Sites / Locations

    Outcomes

    Primary Outcome Measures

    Measuring changes in corneal stiffness parameters in keratoconus after CXL by Corvis ST which measures corneal stiffness parameters.
    Measurement of changes in corneal stiffness parameters { Deformation Amplitude (DAR1), Integrated radius, Stress parameter (SP A1), Stress strain index (SSI) and Corvis biomechanical index (CBI) } before and after crosslinking procedure to measure corneal stiffness.

    Secondary Outcome Measures

    Full Information

    First Posted
    October 19, 2021
    Last Updated
    December 6, 2021
    Sponsor
    Cairo University
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    1. Study Identification

    Unique Protocol Identification Number
    NCT05161052
    Brief Title
    Assessment of Corneal Stiffness in Keratoconus After Crosslinking by Corvis ST and OCT.
    Official Title
    Assessment of Corneal Stiffness Parameters in Keratoconus After Corneal Collagen Cross Linking Using Dynamic Scheimpflug Technology and Anterior Segment Optical Coherence Tomography.
    Study Type
    Interventional

    2. Study Status

    Record Verification Date
    December 2021
    Overall Recruitment Status
    Not yet recruiting
    Study Start Date
    January 1, 2022 (Anticipated)
    Primary Completion Date
    January 1, 2023 (Anticipated)
    Study Completion Date
    February 1, 2023 (Anticipated)

    3. Sponsor/Collaborators

    Responsible Party, by Official Title
    Principal Investigator
    Name of the Sponsor
    Cairo University

    4. Oversight

    Studies a U.S. FDA-regulated Drug Product
    No
    Studies a U.S. FDA-regulated Device Product
    No

    5. Study Description

    Brief Summary
    Objectives: Measurement of corneal stiffness parameters { Deformation Amlitude (DAR1), Integrated radius, Stress parameter (SP A1), Stress strain index (SSI) and Corvis biomechanical index (CBI) } in keratoconic corneas before and after 3 and 6 months CXL using Corvis ST. Measurement of demarcation line depth using anterior segment OCT and correlate between corneal stiffness following CXL and demarcation line depth.
    Detailed Description
    Background and Rationale: Keratoconus is a progressive corneal degeneration resulting from noninflammatory thinning of the corneal stroma. Visual impairment typically commences in adolescence and progresses thereafter. Further increase in myopia, irregular astigmatism, and subepithelial scarring leads to visual impairment. Treatment modalities are based on refractive correction with spectacles or contact lenses to correct astigmatism and restore visual acuity. Such modalities do not stop ectatic progression and further visual deterioration, which ultimately necessitates corneal transplantation in 10% to 20% of patients. Corneal collagen cross-linking (CXL) has emerged as a promising techniq;ue to slow or halt the progression of keratoconus. CXL leads to an increase in intra and interfibrillar covalent bonds by photosensitized oxidation and causes a biomechanical stabilization of the cornea. Corneal visualization using dynamic Scheimpflug technology (Corvis ST, Oculus Optikger€ate GmbH) allows in vivo measurement of the corneal biomechanical deformation response to an applied air puff and is useful for evaluating the biomechanical response parameters of the cornea. It captures the dynamic corneal deformation caused by an air puff using an ultrahigh- speed camera that operates at a speed of greater than 4300 frames per second to capture a series of 140 sequential horizontal Scheimpflug images of the temporal-nasal cross section of the cornea. The consistency of the air puff has been shown and the spatial and temporal profiles have been characterized to allow calculation of the load on the cornea within the imaging window. The Corvis ST enables the measurement of several parameters by analyzing the timing and patterns of deformation at the highest concavity as well as applanation during inward deformation (loading) and outward recovery (unloading). The original parameters have been reported to be influenced most strongly by intraocular pressure (IOP) as well as age and central corneal thickness (CCT). Recently, new corneal biomechanical parameters were introduced, including the Deformation Amplitude ratio at 1.0 mm (DAR1), Deformation Amplitude ratio at 2.0 mm (DAR2), Integrated radius, Stiffness Parameter at first applanation (SP A1), Ambrosio's Relational Thickness (ARTH) , Corbic Biomechanical index (CBI) and biomechanically corrected IOP (bIOP). Laboratory studies have shown that the effective depth of CXL is confined to the anterior 300 μm of the cornea. Moreover, a stromal demarcation line between treated and untreated stroma was visible biomicroscopically at a depth of approximately 300 μm over the entire cornea after CXL treatment. This demarcation line was also evident on optical coherence tomography (OCT). The depth of this line has been postulated as an indirect measurement of cross-linking effectiveness.

    6. Conditions and Keywords

    Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
    Keratoconus

    7. Study Design

    Primary Purpose
    Diagnostic
    Study Phase
    Not Applicable
    Interventional Study Model
    Single Group Assignment
    Model Description
    Measurement of corneal stiffness parameters { Deformation Amplitude (DAR1), Integrated radius, Stress parameter (SP A1), Stress strain index (SSI) and Corvis biomechanical index (CBI) } in keratoconic corneas before and after 3 and 6 months CXL using Corvis ST. Measurement of demarcation line depth using anterior segment OCT and correlate between corneal stiffness following CXL and demarcation line depth.
    Masking
    None (Open Label)
    Allocation
    Randomized
    Enrollment
    55 (Anticipated)

    8. Arms, Groups, and Interventions

    Intervention Type
    Device
    Intervention Name(s)
    Corvis ST (dynamic Scheimpflug technology)
    Other Intervention Name(s)
    OCT (Optical Coherence tomography)
    Intervention Description
    Measurement of corneal stiffness parameters { Deformation Amlitude (DAR1), Integrated radius, Stress parameter (SP A1), Stress strain index (SSI) and Corvis biomechanical index (CBI) } in keratoconic corneas before and after 3 and 6 months CXL using Corvis ST. Measurement of demarcation line depth using anterior segment OCT and correlate between corneal stiffness following CXL and demarcation line depth
    Primary Outcome Measure Information:
    Title
    Measuring changes in corneal stiffness parameters in keratoconus after CXL by Corvis ST which measures corneal stiffness parameters.
    Description
    Measurement of changes in corneal stiffness parameters { Deformation Amplitude (DAR1), Integrated radius, Stress parameter (SP A1), Stress strain index (SSI) and Corvis biomechanical index (CBI) } before and after crosslinking procedure to measure corneal stiffness.
    Time Frame
    Before crosslinknig procedure and after 3, 6 months using Corvis ST.
    Other Pre-specified Outcome Measures:
    Title
    Measuring demarcation line depth in microns by anterior segment OCT. in keratoconus after CXL with demarcation line depth in microns by anterior segment OCT.
    Description
    Measurement of demarcation line depth in the cornea in microns using anterior segment OCT which gives an indicator to corneal stiffness after crosslinking procedure.
    Time Frame
    After 3 and 6 months using anterior segment OCT

    10. Eligibility

    Sex
    All
    Gender Based
    Yes
    Gender Eligibility Description
    Patients between 18- 40 years old with progressive keratoconus undergoing CXL.
    Minimum Age & Unit of Time
    18 Years
    Maximum Age & Unit of Time
    40 Years
    Accepts Healthy Volunteers
    Accepts Healthy Volunteers
    Eligibility Criteria
    Inclusion Criteria: Patients with documented progressive keratoconus within one year include any of the following: A. ≥ 1.00 diopter increase in maximal keratometry (Kmax). B. ≥ 1.00 diopter increase in the manifest cylinder. C. ≥ 0.75 diopter increase in average of Kmax and Kmin (Kmean). D. ≥ 2% decrease in central thickness. E. ≥ 1.50 diopter increase in the central K power from baseline. F. ≥ 1.0 diopter increase in manifest spherical equivalent change (MRSE). All patients have minimal corneal stromal thickness 400 μm before UVA irradiation. Exclusion Criteria: Patients with corneal rings. Advanced keratoconus with corneal scarring. History of herpetic keratitis and severe corneal infection. Pregnancy or breastfeeding. The use of rigid contact lens¬es for more than 4 weeks before the baseline evaluation.
    Central Contact Person:
    First Name & Middle Initial & Last Name or Official Title & Degree
    Mohamed Elnoamany, MD
    Phone
    01222536367
    Email
    mohamedelnoamany1@gmail.com
    First Name & Middle Initial & Last Name or Official Title & Degree
    Mohamed Fakhry, MD
    Phone
    01006678788
    Email
    fakhryref@hotmail.com
    Overall Study Officials:
    First Name & Middle Initial & Last Name & Degree
    Mohamed Fakhry, MD
    Organizational Affiliation
    Cairo University
    Official's Role
    Principal Investigator

    12. IPD Sharing Statement

    Citations:
    PubMed Identifier
    32095205
    Citation
    Salouti R, Bagheri M, Shamsi A, Zamani M. Corneal Parameters in Healthy Subjects Assessed by Corvis ST. J Ophthalmic Vis Res. 2020 Feb 2;15(1):24-31. doi: 10.18502/jovr.v15i1.5936. eCollection 2020 Jan-Mar.
    Results Reference
    background
    PubMed Identifier
    32966284
    Citation
    Nakao Y, Kiuchi Y, Okumichi H. Evaluation of biomechanically corrected intraocular pressure using Corvis ST and comparison of the Corvis ST, noncontact tonometer, and Goldmann applanation tonometer in patients with glaucoma. PLoS One. 2020 Sep 23;15(9):e0238395. doi: 10.1371/journal.pone.0238395. eCollection 2020.
    Results Reference
    background
    PubMed Identifier
    29767348
    Citation
    Herber R, Terai N, Pillunat KR, Raiskup F, Pillunat LE, Sporl E. [Dynamic Scheimpflug Analyzer (Corvis ST) for measurement of corneal biomechanical parameters : A praxis-related overview]. Ophthalmologe. 2018 Aug;115(8):635-643. doi: 10.1007/s00347-018-0716-y. German.
    Results Reference
    background

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    Assessment of Corneal Stiffness in Keratoconus After Crosslinking by Corvis ST and OCT.

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