Material and Methods: The right eyes of 156 healthy volunteers were included in the study. Participants did not have a history of drug use and systemic illness and ocular surgery. Patients with 3.0 D or more astigmatism or 4.0 D or more spherical refractive error and history of previous contact lens use (within 4 weeks for rigid contact lenses and within 2 weeks for soft contact lenses) were also excluded. Anterior chamber depth (ACD), central corneal thickness (CCT), keratometry (K) [Flattest K (Kf), steepest K (Ks) and mean K (Km)] measurements obtained with Pentacam and Nidek AL-Scan optical biometer were compaired.

Results: Nidek AL Scan underestimated CCT measurements compared with Pentacam (p<0,001 and mean difference was -13.41 micrometers). Pearson correlation analysis determined signifi cant positive correlations between Nidek AL Scan and Pentacam in terms of CCT (r=0.981, p<0.001), ACD (r=0.983, p<0.001), Kf (r=0.990,p<0.001), Ks (r=0.990, p<0.001) and Km (r=0.991, p<0.001) The Bland-Altman plots showed narrow limits of agreement for ACD, Kf, Ks and Km parameters. However, the limits of agreement for CCT were broad and moderate agreement was found for this parameter.

Conclusions: Good agreement was found in Ks, Kf, Km and ACD parameters between Nidek AL Scan and Pentacam. On the other hand these devices do not seem to be interchangeable for pachymetric determination. Keywords : Anterior chamber depth, central corneal thickness; keratometry, nidek AL scan optical biometry, pentacam, scheimpflug