Biomechanical Properties of Keratoconic Eyes

January 22, 2019 updated by: Dr Phillip J Buckhurst, University of Plymouth
In keratoconus (KC) corneal thinning and protrusion can cause myopia and irregular astigmatism, affecting vision. The biomechanical properties of the cornea is maintained by an intricate collagen network, which is responsible for its shape and function. In KC this collagen network is disrupted resulting in the cornea losing its shape and function. Keratoconic changes are focal and localised to certain regions of the cornea and the early detection of these changes is challenging. Screening methods include corneal topography (evaluation of anterior corneal surface curvature), tomography (assessing the morphological features of the anterior segment) and aberrometry (measuring the optical aberrations of the eye). More recent research suggests that the biomechanical destabilization of the cornea may precede topographic and tomographic evidence of KC. Management of KC depends on disease severity with severe cases being treated with keratoplasty and less severe cases with cornealcollagencrosslinking (CXL). CXL is an emerging technique, which aims to increase the biomechanical strength of the keratoconic cornea. Despite strong evidence of changes in the biomechanical properties in human corneas following CXL, there is a significant need for accurate measures of biomechanical changes in vivo pre and post CXL. Until recently technical limitations have restricted the ability to assess the biomechanical properties of the whole cornea in vivo. With the introduction of the CorvisST (Oculus) it is now possible to assess regional biomechanical behaviour of the cornea. The output from the device provides a variety of parameters to indicate the cornea's biomechanical strength. To date, the association between the deflection behaviours in various regions of the cornea in keratoconic eyes preand post CXL has not been studied. In order to effectively assess the clinical benefits of CXL such information is vital. The primary goal of this investigation is to investigate regional biomechanical properties of the keratoconic eye before and after CXL.

Study Overview

Status

Status

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

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Study Type

Study Type

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Observational

Enrollment (Anticipated)

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.
35

Contacts and Locations

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Study Contact

Study Contact

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Study Contact Backup

Study Locations

Participation Criteria

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Eligibility Criteria

Eligibility Criteria

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Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Potential participants will be identified as those patients who are due to undergo corneal collagen crosslinking treatment

Description

Inclusion Criteria:

  • Adult subjects over the age of 18 with keratoconus who are enrolled for collagen crosslinking treatment

Exclusion Criteria:

  • Any patient who has had surgical complications will also be excluded from participation in the study.

Determination during enrolment:

  • Pregnancy or breastfeeding during the study
  • Any kind of systemic disease which affect collagen and the body water regulation system (Marfan syndrome, osteogenesis imperfect, pseudozanthoma elasticum, EhlersDanlos, diabetes, rosacea, acne, cardiovascular disease, thyroid disease)

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

  • Observational Models: Cohort
  • Time Perspectives: Prospective

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
Change of the corneal hysteresis following corneal crosslinking (mmHg)
Time Frame: Up to 3 months prior to corneal collagen crosslinking treatment and at 3-6 months after treatment
Corneal hysteresis as measured using the CorvisST
Up to 3 months prior to corneal collagen crosslinking treatment and at 3-6 months after treatment

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
Change of refractive error following corneal crosslinking (LogMAR)
Time Frame: Up to 3 months prior to corneal collagen crosslinking treatment and at 3-6 months after treatment
Refractive error measured using objective refraction
Up to 3 months prior to corneal collagen crosslinking treatment and at 3-6 months after treatment
Axial Length prior to corneal crosslinking (mm)
Time Frame: Up to 3 months prior to corneal collagen crosslinking treatment
Axial length determined with the LenStar
Up to 3 months prior to corneal collagen crosslinking treatment
Axial Length axial length following corneal crosslinking (mm)
Time Frame: At 3-6 months after treatment
Axial length determined with the LenStar
At 3-6 months after treatment
Change in corneal curvature following corneal crosslinking (mm)
Time Frame: Up to 3 months prior to corneal collagen crosslinking treatment and at 3-6 months after treatment
Corneal curvature assessed with the Pentacam HR
Up to 3 months prior to corneal collagen crosslinking treatment and at 3-6 months after treatment
Tear break up time prior to corneal crosslinking (s)
Time Frame: Up to 3 months prior to corneal collagen crosslinking treatment
Tear break up time determined using the Oculus K5
Up to 3 months prior to corneal collagen crosslinking treatment
Tear break up time following corneal crosslinking (s)
Time Frame: At 3-6 months after treatment
Tear break up time determined using the Oculus K5
At 3-6 months after treatment

Collaborators and Investigators

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Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Plymouth

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.
June 1, 2015

Primary Completion (Anticipated)

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.
December 1, 2019

Study Completion (Anticipated)

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.
January 1, 2020

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).
June 14, 2015

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.
June 18, 2015

First Posted (Estimate)

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.
June 19, 2015

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.
January 23, 2019

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.
January 22, 2019

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.
January 1, 2019

More Information

Terms related to this study

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.
  • 15/SW/0107

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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