Material and Methods: This study comprised of sixty eyes of 30 healthy subjects. Central corneal thickness (CCT), aqueous depth (AD:corneal endothelium to lens), anterior chamber depth (ACD: corneal epithelium to lens), keratometry measurements (K in the steepest and flattest meridian) and white-to-white (WTW) distance derived from both devices were compared. All measurements were repeated five times for Lenstar and three times for Sirius by the same physician and mean of these measurements were used for comparisons.

Results: The CCT measurements were significantly higher whereas AD and ACD measurements were lower with Lenstar (p<0.05). Mean differences for CCT, AD, and ACD were 3.93±6.65 μm, -0.08±0.04 mm, and -0.07±0.03 mm, respectively. There were no statistically significant differences between the devices for the steep and flat K values and mean WTW distance (p>0.05). Pearson correlation analysis showed high correlation between the 2 devices for all measurements (r>0.90, p<0.05). On Bland-Altman analysis, 95% limits of agreement for all measurements were within clinically acceptable limits and there was good agreement between the 2 devices.

Conclusion: Anterior segment parameters evaluated with Lenstar LS 900 optical biometer and Sirius anterior segment analysis system were correlated well with each other and measurement differences between the devices were clinically negligible. Therefore, it was concluded that both devices can be used interchangeably for the most clinical purposes. Keywords : Lenstar, sirius, anterior segment parameters