Corneal topography

Reproducibility

Limits of agreement

Statistics

Repeatability

Materials science

Ophthalmology

Intraclass correlation

Cornea

Scheimpflug principle

Keratometer

Astigmatism

LASIK

Physics

Mathematics

Optics

Coefficient of variation

Optical coherence tomography

Medicine

Nuclear medicine

Optometry

Refractive surgery

Journal of Cataract & Refractive Surgery

Purpose To evaluate the repeatability of automatic measurements by a new anterior segment optical coherence tomographer (AS-OCT) combined with Placido topography and their agreement with those provided by 2 rotating Scheimpflug cameras. Setting G.B. Bietti Foundation IRCCS, Rome, Italy. Design Evaluation of a diagnostic test instrument. Methods Unoperated eyes and eyes with previous myopic excimer laser surgery were analyzed. Three consecutive scans were acquired with an AS-OCT device (MS-39) and 1 with 2 rotating Scheimpflug cameras (Pentacam HR and Sirius). The following parameters were evaluated: simulated keratometry, posterior and total corneal power, total corneal astigmatism, corneal asphericity, thinnest corneal thickness, central epithelial thickness, corneal diameter, and aqueous depth. Repeatability was assessed using test–retest variability, the coefficient of variation (CoV), and the intraclass correlation coefficient; agreement was assessed by the 95% limits of agreement. Results The study comprised 96 unoperated eyes and 43 eyes with previous myopic excimer laser surgery. High repeatability was achieved in both groups, as shown by a CoV less than 1.0% for most parameters. The repeatability of epithelial thickness was slightly lower than that of the whole corneal thickness, although the CoV was still good (1.87% in unoperated eyes; 3.28% in post-refractive surgery eyes). Moderate repeatability was found for total corneal astigmatism measurements, with a CoV greater than 20.0%. Agreement with Scheimpflug cameras was high for aqueous depth and thinnest corneal thickness and moderate for most other parameters. Conclusion The high repeatability of automatic measurements by the new AS-OCT device supports its use in clinical practice.

Repeatability of automatic measurements by a new anterior segment optical coherence tomographer combined with Placido topography and agreement with 2 Scheimpflug cameras