Comparison of optical low coherence interferometry and Scheimpflug imaging combined with partial coherence...

The purpose of the study was to evaluate the agreement between measurements by optical low-coherence interferometry (OLCI, Aladdin) and those by Scheimpflug imaging combined with partial coherence interferometry (Scheimpflug-PCI, Pentacam AXL) in cataract patients.

This was a retrospective comparative study conducted in the United Arab Emirates. Axial length (AL), corneal power (keratometry, K), anterior chamber depth (ACD), and corneal astigmatism in patients with cataracts were measured with both devices. Difference and correlation were evaluated with paired t-test (p) and Pearson's correlation coefficient^®, respectively.

A total of 164 eyes of 95 patients were analyzed (164 eyes for K, 155 for ACD, and 112 for AL). The mean AL taken by OLCI was longer than that by Scheimpflug-PCI (23.25 mm vs. 23.23 mm, P ≤ 0.0001), showing an excellent correlation between the two (r = 0.9990). ACD measured by OLCI was 0.08 mm shallower than that by Scheimpflug-PCI (P = 0.0003, r = 0.7386). Corneal power measured by OLCI was lower than that by Scheimpflug-PCI (differences in mean K, flat K, and steep K were 0.05 diopters (D), 0.08 D, and 0.02 D, respectively), showing very strong correlations between the two devices (r = 0.9614, 0.9445, and 0.9535, respectively). Only flat K values measured with the two devices were significantly different (P = 0.0428). There were no statistically significant differences in the magnitude of astigmatism or J45 vector between the two devices (P = 0.1441 and P = 0.4147, respectively). However, J0 vector values were significantly different (P = 0.0087).

Although OCLI and Scheimpflug-PCI showed strong correlations for measurements of AL, K, ACD, and corneal astigmatism in cataract patients, there were small but statistically significant differences in AL, ACD, flat K, and J0 vector. Thus, these two devices are not interchangeable for calculating intraocular lens power.