Clinical trial NCT01527708: Accuracy of Curvature and Wavefront Aberrations of Posterior Corneal Surface, in Keratoconic and Post-CXL Corneas
Official title: Repeatability, Reliability and Reproducibility of Pentacam-derived Curvature and Wavefront Aberrations of Posterior Corneal Surface, in Keratoconic and Cross-linked Corneas
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Keratoconus
Lead sponsor: Democritus University of Thrace
Sponsor class: OTHER
First posted: 2012-02-07
Enrollment: 129
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_CONTROL
Time perspective: PROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: Participants were recruited from the Cornea service of the EIT in a consecutive-if-eligible basis.

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.

Eligibility criteria: 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

Primary outcomes:
measure: Variability of posterior corneal surface curvature and aberrometric measurements within and between sessions and within and between observers.
timeFrame: 2 weeks
Secondary outcomes:
Other outcomes:
Locations:
city: Alexandroupolis
country: Greece
facility: Eye Institute of Thrace (EIT)
state: Thrace
Study officials:
affiliation: Democritus University of Thrace
name: Georgios Labiris, Lecturer
role: PRINCIPAL_INVESTIGATOR
References: