Accuracy of Curvature and Wavefront Aberrations of Posterior Corneal Surface, in Keratoconic and Post-CXL Corneas

Completed

• Conditions: Keratoconus
• Interventions: Procedure: Corneal Collagen Cross-linking (CXL)

• Registration Number: NCT01527708
• Lead Sponsor: Democritus University of Thrace

Brief Summary

Primary objective of this study was to assess the intrasession, intersession and interobserver variability of the Pentacam-derived curvature and zernike coefficients in back surface of normal, keratoconic and crosslinked corneas.

Detailed Description

The Pentacam Classic (Oculus Optikgerate GmbH, Heidelberg, Germany, software version 1.14r04) was used for the sake of the study.Three study groups were formed: 1) Normal 2) Keratoconus group (KC) included patients with progressive keratoconus and 3) 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. Keratometry (K), asphericity (Q), best-fit toric ellipsoid radius (Rs), eccentricity (ecc) and aberrometry (6.0mm pupil diameter), were analyzed. Furthermore we calculated and studied CRMS and CLRMS in order to better appreciate the visual significance of HOAs. Precision (Pre), repeatability (COR) and intraclass correlation coefficient (ICC), were calculated for evaluating intrasession and intersession repeatability. Bland-Altman analysis was used for assessing interobserver repeatability.

Study Timeline

• Study Start: 2011-09
• Primary Completion: 2011-11
• Study Completion: 2011-12
• Status Verified: 2012-01
• Study First Submitted: 2012-02-03
• Study First Submitted QC: 2012-02-03
• Last Update Submitted: 2012-02-03
• Study First Posted: 2012-02-07
• Last Update Posted: 2012-02-07

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 129

Inclusion Criteria

• Ideal refractive surgery candidate (Normal Group)
• Progressive keratoconus (Keratoconus group)
• Corneal collagen cross linking (CxL) treatment at least one year prior to enrollment (CxL group)

Exclusion Criteria

(Normal Group)

• No indications of corneal pathology in slit-lamp biomicroscopy and Placido disk-based videokeratography
• Uneventful ophthalmologic history

All groups:

• Glaucoma
• Suspicion of glaucoma
• history of herpetic keratitis
• corneal scarring
• severe eye dryness
• pregnancy or nursing
• current corneal infection
• underlying autoimmune disease

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Collagen-Cross-linking group (CXLG)	Corneal Collagen Cross-linking (CXL)	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.

Primary Outcome Measures

Name	Time	Method
Variability of posterior corneal surface curvature and aberrometric measurements within and between sessions and within and between observers.	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 reliability of all measurements was evaluated by means of the intraclass correlation coefficient(ICC).

Trial Locations

Locations (1)

Eye Institute of Thrace (EIT); 🇬🇷 Alexandroupolis, Thrace, Greece