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
About this trial
This is an interventional diagnostic trial for Keratoconus
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.
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
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
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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
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Assessment of Corneal Stiffness in Keratoconus After Crosslinking by Corvis ST and OCT.
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