Repeatability and reproducibility of Galilei measurements in normal keratoconic and postrefractive corneas

Objective: To assess the repeatability and reproducibility of the anterior segment measurements performed with a dual Scheimpflug analyzer (Galilei) in normal, keratoconic and post-refractive surgery corneas.

Methods: To evaluate the repeatability, two additional measurements were performed by the first examiner. To assess reproducibility, this was later followed by a single reading by the second examiner. The following parameters were recorded and evaluated in this study; central corneal thickness (CCT), thinnest corneal thickness (TCT), mean total corneal power (TCP) in central (0-4mm), mean posterior corneal power (PCP) in central (0.5-2mm), anterior and posterior elevation (best fit sphere [BFS]) in central 8mm anterior and posterior eccentricity (ɛ(2)) in central 8mm. Repeatability and reproducibility for each corneal parameter was assessed using the Bland-Altman analysis.

Results: Each of the three groups was consisted of 20 subjects (totally 60 patients, 30 men and 30 women). The 95% LoA for repeatability was very small, indicating small discrepancies between measurements related to CCT. Acceptable repeatability was also achieved for the other parameters in each group. However, the 95% LoA for value TCP was larger in keratoconic eyes. The 95% LoA for reproducibility was also very small, and acceptable for all measured parameters in each group. In addition, the 95% LoA was larger for the measurement of CCT and TCT for postrefractive corneas.

Conclusions: The anterior segment measurements provided by Galilei showed good repeatability and reproducibility for normal, keratoconic and postrefractive corneas.