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

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.

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Key information

Conditions

Keratoconus Corneal Diseases Eye Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Eye Institute of Thrace (EIT)

Alexandroupoli, Thrace, 68100, Greece

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Corneal Collagen Cross-Linking (CxL)

Procedure

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.

Primary outcomes

Variability of posterior corneal surface curvature and aberrometric 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 reliability of all measurements was evaluated by means of the intraclass correlation coefficient(ICC).

Sponsors and collaborators

Lead sponsor

Democritus University of Thrace

Other

Registry information

Official study title

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

Important dates

Study start: 2011
Primary completion: 2011
Study completion: 2011
First posted: Feb 7, 2012
Registry last updated: Feb 7, 2012

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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Completed