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Variability of Pentacam-derived Back Elevation Measurements in Keratoconus and Cross-linked Corneas

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT01471873
First Posted: November 16, 2011
Last Update Posted: January 18, 2017
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by (Responsible Party):
Georgios Labiris, Democritus University of Thrace
  Purpose
Primary objective of this study was to assess the intrasession, intersession and interobserver variability of the Pentacam-derived posterior corneal elevation measurements in keratoconus eyes and eyes that underwent Corneal Collagen Cross-liknking (CxL) treatment due to progressive keratoconus.

Condition Intervention
Keratoconus Procedure: Corneal Collagen Cross-linking (CXL)

Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Prospective
Official Title: Variability of Pentacam-derived Back Elevation Measurements in Keratoconus and Cross-linked Corneas

Resource links provided by NLM:


Further study details as provided by Georgios Labiris, Democritus University of Thrace:

Primary Outcome Measures:
  • Variability of posterior corneal surface elevation measurements within and between sessions and within and between observers. [ Time Frame: 2 weeks ]
    The Pentacam Classic (Oculus Optikgerate GmbH, Heidelberg, Germany, software version 1.14r04) was used for the sake of the study. Three consecutive scans were obtained by two experienced operators for the assessment of intrasession and interobserver variability. The same procedure was repeated within two weeks for the assessment of intersession variability.Bland-Altman plots were used to evaluate agreement between the 2 operators. The reproducibility of all measurements was evaluated by means of the intraclass correlation coefficient(ICC).


Enrollment: 67
Study Start Date: March 2011
Study Completion Date: November 2011
Primary Completion Date: September 2011 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
Keratoconus Group (KG)
Keratoconus group (KG) included patients with progressive keratoconus.
Collagen-Cross-linking group (CXLG)
Collagen-Cross-linking group (CXLG) included keratoconus patients that had been treated with uneventful corneal collagen cross-linking (CXL) at least on year prior to their enrolment in the study.
Procedure: Corneal Collagen Cross-linking (CXL)

The same surgical procedure was applied to all CXLG patients that included:

Instillation of proparacaine hydrochloride 0.5% drops for topical anaesthesia, application of a sponge saturated with 10% alcohol to the central cornea for 20-30 seconds and subsequent de-epithelialization by means of a hockey knife. Following de-epithelialization, a mixture of 0.1% riboflavin in 20% Dextran solution was instilled to the cornea for 30 minutes (2 drops every 2 minutes) prior to the irradiation. In details, an 8.0mm diameter of central cornea was irradiated for 30 minutes by UVA light with a wavelength of 370nm and an irradiance of 3mW/cm2.The UVA radiation source that was used is the UV-XTM (IROC AG, Zurich, Switzerland). Instillation of riboflavin drops (1 drop every 2 minutes) was continued during irradiation, as well.


Detailed Description:

The Pentacam Classic (Oculus Optikgerate GmbH, Heidelberg, Germany, software version 1.14r04) was used for the sake of the study.Two study groups were formed: 1) Keratoconus group (KC) included patients with progressive keratoconus and 2) Collagen-Cross-linking group (CXL) included keratoconus patients that had been treated with uneventful CXL at least on year prior to their enrollment in the study.

Three consecutive scans were obtained by two experienced operators. The same procedure was repeated within two weeks for the assessment of intersession variability. In all cases acceptable maps had at least 10.0mm of corneal coverage.All back elevation points were codified in order to facilitate statistical processing of data. Further to single point analysis, three additional parameters were evaluated: a) zone 4 parameter (z4) which derived by the analysis of all points at the central 4.0mm diameter zone, b) zone 8 parameter (z8) which derived by the analysis of all points at the central 8.0mm diameter zone, and, c) highest elevation point parameter (HEP), which derived by the analysis of the highest elevation points for all participants. Reproducibility of measurements was evaluated by means of intraclass correlation coefficients (ICC). Three different ICC types were calculated: a) intrasession ICC for both operators (ICC1 & ICC2), b) interobserver ICC, and, c) intersession ICC. Moreover, Bland-Altman plots were used to evaluate the level of agreement between the two operators.

  Eligibility

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Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
Participants were recruited from the Cornea service of the EIT in a consecutive-if-eligible basis.
Criteria

Inclusion Criteria:

  • Progressive keratoconus (Keratoconus group)
  • Corneal collagen cross linking (CxL) treatment at least one year prior to enrollment (CxL group)

Exclusion Criteria:

  • Glaucoma
  • Suspicion of glaucoma
  • history of herpetic keratitis
  • corneal scarring
  • severe eye dryness
  • pregnancy or nursing
  • current corneal infection
  • underlying autoimmune disease
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01471873


Locations
Greece
Eye Institute of Thrace (EIT)
Alexandroupolis, Thrace, Greece, 67100
Sponsors and Collaborators
Democritus University of Thrace
  More Information

Publications:
Responsible Party: Georgios Labiris, Senior Lecturer of Ophthalmology, Democritus University of Thrace
ClinicalTrials.gov Identifier: NCT01471873     History of Changes
Other Study ID Numbers: 25/27-09-2011
First Submitted: November 9, 2011
First Posted: November 16, 2011
Last Update Posted: January 18, 2017
Last Verified: January 2017

Keywords provided by Georgios Labiris, Democritus University of Thrace:
Posterior corneal surface elevation
Pentacam-Scheimpflung imaging
variability
progressive keratoconus
corneal cross-linking

Additional relevant MeSH terms:
Keratoconus
Corneal Diseases
Eye Diseases