Comparison between spectral-domain optical coherence tomography-based and partial coherence interferometry-based biometry

We compared axial length (AL) measurements using spectral-domain optical coherence tomography (SD-OCT)-based and partial coherence interferometry (PCI)-based biometry in eyes with various chorioretinal diseases. Medical records were retrospectively analyzed in 123 eyes from 73 patients who underwent AL measurements using SD-OCT and PCI. AL values were highly consistent by both measurements (ICC = 0.996 in SD-OCT and 0.995 in PCI-based biometry). The mean difference in AL between the two instruments was - 0.09 +/- 0.17 mm, which was significant (P < 0.001). There was a strong correlation between the measurements obtained using the two instruments (r = 0.982, P < 0.001). The 95% limits of agreement were - 0.43 to 0.25 mm, and the agreement of AL in the Bland-Altman analysis showed a difference. The difference in measurements was not associated with the difference in central retinal thickness (r = 0.033, P = 0.720). However, the presence of an epiretinal membrane affected the difference in measurements, unlike in other chorioretinal diseases (P = 0.014). SD-OCT-based biometry showed a good correlation with PCI-based biometry in the measurement of AL; however, the mean AL between the two instruments was significantly different. Therefore, AL measurements made using SD-OCT-based and PCI-based biometry are not interchangeable.