NCT01471873

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

• Status: Completed
• Phase: —
• Study type: Observational
• Enrollment: 67 (actual)
• Sponsor: Democritus University of Thrace · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

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.

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.

Conditions

• Keratoconus

Interventions

Type	Name	Description
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.

Timeline

• Start date: 2011-03-01
• Primary completion: 2011-09-01
• Completion: 2011-11-01
• First posted: 2011-11-16
• Last updated: 2017-01-18

Locations

1 site across 1 country: Greece