Comparison of a new anterior segment optical coherence tomography and Oculus Pentacam for measurement of anterior chamber depth and corneal thickness

Background: Accurate measurements of anterior chamber depth (ACD) and regional corneal thickness are especially important for the diagnosis and treatment of many ocular disease. This study aimed to evaluate the repeatability and reliability of a new swept source anterior segment optical coherence tomography (AS-OCT) and its agreement with Oculus Pentacam for measurements of ACD and corneal thickness (CT). Methods: The central corneal thickness (CCT), superior corneal thickness (SCT), inferior corneal thickness (ICT), nasal corneal thickness (NCT), temporal corneal thickness (TCT) and ACD of the right eye from forty-nine adults aged 18 to 36 years (24.78 +/- 4.36 years old) were measured with Pentacam and AS-OCT (CASIA2). All subjects were measured twice with each device. The repeatability was determined using the coefficient of repeatability (COR), the relative COR and the limits of agreement (LOA). Bland-Altman plot was also used for evaluating the agreement between parameters from the two devices. Results: For the repeatability of CASIA2, the COR of the two measurements of ACD, CCT, SCT, ICT, NCT and TCT was 0.31 mm, 18.58, 25.83, 28.32, 26.71 and 22.09 mu m respectively. There were no statistically significant differences between the CT and ACD measurements by CASIA2 (P>0.05). For measurements with Pentacam and CASIA2, the COR of ACD, CCT, SCT, NCT, ICT and TCT was 0.294 mm, 13.10, 51.57, 48.06, 56.21 and 47.69 mu m respectively. No significant differences were found between the values measured by CAISA2 and Pentacam for CT and ACD (P>0.05). The Bland-Altman analysis also suggested high consistency between measurements obtained by Pentacam and CASIA2. Conclusions: Our results suggest that Pentacam and CASIA2 have good agreement in CT and ACD measurements. The two devices can be considered interchangeable for these parameters' measurements in healthy subjects when monitoring corneal conditions or planning ocular surgery. However, subtle differences between CASIA2 and Pentacam should also be kept in mind for certain specific clinical or research purposes.