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

Sponsor

Democritus University of Thrace (Other)

Overall Status

Completed

CT.gov ID

NCT01527708

Collaborator

(none)

129

Enrollment

Location

Duration (Months)

43.1

Patients Per Site Per Month

Study Details

Study Description

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.

Condition or Disease	Intervention/Treatment	Phase
Keratoconus	Procedure: Corneal Collagen Cross-linking (CXL)

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 Design

Study Type:

Observational

Actual Enrollment :

129 participants

Observational Model:

Case-Control

Time Perspective:

Prospective

Official Title:

Repeatability, Reliability and Reproducibility of Pentacam-derived Curvature and Wavefront Aberrations of Posterior Corneal Surface, in Keratoconic and Cross-linked Corneas

Study Start Date :

Sep 1, 2011

Actual Primary Completion Date :

Nov 1, 2011

Actual Study Completion Date :

Dec 1, 2011

Arms and Interventions

Arm	Intervention/Treatment
Keratoconus Group (KCG) Keratoconus group (KCG) 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) 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.
Normal Group (NG) Normal group (NG) was formed by refractive surgery candidates who visited EIT's refractive surgery service for their preoperative examination. Eligibility for participation in the NG was confirmed by consecutive topographies, while all NG participants had to present uneventful ophthalmologic history, no indications of corneal pathology in slit-lamp biomicroscopy and Placido disk-based videokeratography.

Arm

Intervention/Treatment

Keratoconus Group (KCG)

Keratoconus group (KCG) 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)

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.

Normal Group (NG)

Normal group (NG) was formed by refractive surgery candidates who visited EIT's refractive surgery service for their preoperative examination. Eligibility for participation in the NG was confirmed by consecutive topographies, while all NG participants had to present uneventful ophthalmologic history, no indications of corneal pathology in slit-lamp biomicroscopy and Placido disk-based videokeratography.

Outcome Measures

Primary Outcome Measures

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).

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

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

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Eye Institute of Thrace (EIT)	Alexandroupolis	Thrace	Greece	68100

Sponsors and Collaborators

Democritus University of Thrace

Investigators

Principal Investigator: Georgios Labiris, Lecturer, Democritus University of Thrace

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

Responsible Party:

Georgios Labiris, Lecturer, Democritus University of Thrace

ClinicalTrials.gov Identifier:

NCT01527708

Other Study ID Numbers:

27/27-09-11

First Posted:

Feb 7, 2012

Last Update Posted:

Feb 7, 2012

Last Verified:

Jan 1, 2012

Additional relevant MeSH terms:

Keratoconus

Study Results

No Results Posted as of Feb 7, 2012