Abstract
Purpose :
to investigate the repeatability of automatic measurements provided in keratoconic eyes by a new AS-OCT device combined with Placido-disk corneal topography (MS-39,CSO, Florence, Italy) and to assess their agreement with the corresponding measurements taken with a rotating Scheimpflug camera combined with Placido-disktopography (Sirius, CSO,Florence, Italy).
Methods :
Three consecutive scans were acquired with an AS-OCT device (MS-39) and one with rotating Scheimpflug cameras (Sirius). The measured parameters were: 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 investigated by test–retest variability, the coefficient of variation (CoV), and the intraclass correlation coefficient. The level of agreement was assessed by the 95% limits of agreement
Results :
The study enrolled 44 eyes affected by keratoconus. High repeatability (CoV less than 1.0%) was obtained for corneal diameter, simulated K, total corneal power and aqueous depth, whereas ICC was more than 0.90 with all parameters. Compared with the Scheimpflug camera, the AS-OCT Placido topographer provided higher simulated K and TCP values. The mean difference was 0.63D and 1.59D respectively. Statistically, but not clinically, significant differences were found for posterior corneal power, total corneal power, anterior Q value and corneal diameter (p≤0.01). Agreement with Scheimpflug cameras was high for aqueous depth and moderate for most other parameters.
Conclusions :
The new AS-OCT device provided high repeatability and good agreement with Scheimpflug camera measures in keratoconic eyes. This suggests the new device to be a valid instrument in clinical practice.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.