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

Democritus University of Thrace

Status: Completed

Conditions: Keratoconus

Treatments: Procedure: Corneal Collagen Cross-linking (CXL)

Study type: Observational

Funder types: Other

Identifiers

NCT01527708

27/27-09-11

Details and patient eligibility

About

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.

Full 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.

Enrollment: 129 patients

Sex: All

Ages: 18+ years old

Volunteers: No 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

Trial design

129 participants in 3 patient groups

Keratoconus Group (KCG)

Description:

Keratoconus group (KCG) included patients with progressive keratoconus.

Collagen-Cross-linking group (CXLG)

Description:

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.

Treatment:

Procedure: Corneal Collagen Cross-linking (CXL)

Normal Group (NG)

Description:

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.