Comparison of Optical Low-coherence Interferometry and Scheimpflug Imaging Combined with Partial Coherence Interferometry Biometers in Cataract Patients

Abstract

Background: To evaluate the agreement between the biometers measured by optical low-coherence interferometry (OLCI, Aladdin) and those measured by Scheimpflug imaging combined with partial coherence interferometry (Scheimpflug-PCI, Pentacam AXL) in cataract patients.Methods: The axial length (AL), corneal power (keratometry, K), anterior chamber depth (ACD), and corneal astigmatism were measured with the two devices in patients with cataracts. The difference and correlation were evaluated with a paired t-test (p) and Pearson’s correlation coefficient (r), respectively.Results: One hundred sixty-four eyes of 95 patients were analyzed. The mean AL taken by OLCI was longer with excellent correlation (OLCI 23.25 mm, Scheimpflug-PCI 23.23 mm, p = < 0.0001, r = 0.9990). OLCI measured the ACD 0.08 mm shallower than Scheimpflug-PCI (p = 0.0003, r = 0.7386). The difference was statistically significant for flat K (p = 0.0428). The mean K and steep K were not significantly different. Vector analysis showed no statistically significant difference in the magnitude of astigmatism and the oblique vector between the two devices (p = 0.1441 and p = 0.4147, respectively). Only the cardinal vector was different (p = 0.0087).Conclusions: Although OCLI and Scheimpflug-PCI showed strong correlations for AL, K, ACD, and corneal astigmatism in cataract patients, there were small but statistically significant differences in the AL, ACD, flat K, and cardinal vector. The two devices are not interchangeable for calculating intraocular lens power.

Agreements’ profile of Scheimpflug-based optical biometer with gold standard partial coherence interferometry

“…A similar finding was previously reported in a study by Kim and Han [28] In that study; the authors attributed this discrepancy to the error of the Pentacam AXL and recommended that it is necessary to check the extra-ordinary AL values measured by the Pentacam AXL with another device. In all three groups of normal, pseudophakic, and cataractous eyes, the mean difference of the AL between the two devices increased with increasing AL.…”

“…Table 4 shows a summary of the findings of the previous studies in this regard. As seen in Table 4, the difference between Pentacam AXL and other biometric devices has been reported in a range of 0.002 to 0.08 mm [1,8,[11][12][14][15][16]18,22,24,[28][29][30] . However, the LoA is diverse among previous studies, possibly due to different sample characteristics, measurement conditions, or measurement devices.…”