Agreement Between Lenstar LS900, Pentacam, and Sirius Devices in Terms of Anterior Segment Parameter Measurements in Keratoconic and Healthy Eyes

Purpose To assess the agreement of the Lenstar LS900 (Haag-Streit AG), Sirius (CSO), and Pentacam HR (Oculus Optikgeräte GmbH) devices in terms of anterior chamber depth (ACD), flat (K1) and steep (K2) axis keratometry, white-to-white corneal diameter (WTW), and pupil diameter (PD) measurements in healthy eyes and keratoconus cases. Methods Measurements were obtained using the Lenstar LS900, Sirius, and Pentacam HR by an experienced technician who was blinded to the results from each modality. The agreement between the devices was evaluated with a Bland-Altman analysis. Results One hundred thirty-eight eyes of 138 patients (73 healthy, 65 keratoconus) were examined. There was no proportional error in the K1 and K2 measurements of the devices in healthy eyes ( P > .05). In keratoconus cases, there was a proportional error between the K1 and K2 measurements of the devices (for K1, the Lenstar vs the Sirius: P < .001, R 2 = 0.634, the Lenstar vs the Pentacam: P < .001, R 2 = 0.322, the Sirius vs the Pentacam: P < .001, R 2 = 0.333; for K2, the Lenstar vs the Sirius: P < .001, R 2 = 0.666, the Lenstar vs the Pentacam: P < .001, R 2 = 0.514, the Sirius vs the Pentacam: P < .001, R 2 = 0.523)). There was no proportional error between the ACD and WTW measurements of the devices in healthy cases and keratoconus cases ( P > .05). Compatibility in PD measurements was noted only between the Lenstar and Pentacam in both groups ( P > .05). Conclusions The three devices demonstrated agreement for ACD and WTW. The Lenstar LS900 and Pentacam HR were compatible in PD. Keratometry values were in agreement between the three devices in healthy eyes. This agreement did not hold in keratoconus. Using these devices interchangeably to evaluate keratometry in keratoconus may yield misleading results. [ J Refract Surg . 2025;41(7):e690–e701.]