Comparison of composite and segmental methods for acquiring optical axial length with swept-source optical coherence tomography

So Goto; Naoyuki Maeda; Toru Noda; Kazuhiko Ohnuma; Shizuka Koh; Ikko Iehisa; Kohji Nishida

doi:10.1038/s41598-020-61391-7

Comparison of composite and segmental methods for acquiring optical axial length with swept-source optical coherence tomography

Sci Rep. 2020 Mar 11;10(1):4474. doi: 10.1038/s41598-020-61391-7.

Authors

So Goto^{1

2

3}, Naoyuki Maeda⁴, Toru Noda², Kazuhiko Ohnuma⁵, Shizuka Koh¹, Ikko Iehisa², Kohji Nishida^{1

6}

Affiliations

¹ Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
² Department of Ophthalmology, National Hospital Organization, Tokyo Medical Center, Tokyo, Japan.
³ School of Optometry and Vision Science, University of California Berkeley, California, 94720, USA.
⁴ Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan. nmaeda@ophthal.med.osaka-u.ac.jp.
⁵ Laboratorio de Lente Verde, Chiba, Japan.
⁶ Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Osaka, Japan.

Abstract

This study compared the optical axial length (AL) obtained by composite and segmental methods using swept-source optical coherence tomography (SS-OCT) devices, and demonstrated its effects on the post-operative refractive errors (RE) one month after cataract surgery. Conventional AL measured with the composite method used the mean refractive index. The segmented-AL method used individual refractive indices for each ocular medium. The composite AL (24.52 ± 2.03 mm) was significantly longer (P < 0.001) than the segmented AL (24.49 ± 1.97 mm) among a total of 374 eyes of 374 patients. Bland-Altman analysis revealed a negative proportional bias for the differences between composite and segmented ALs. Although there was no significant difference in the RE obtained by the composite and segmental methods (0.42 ± 0.38 D vs 0.41 ± 0.36 D, respectively, P = 0.35), subgroup analysis of extremely long eyes implanted with a low power intraocular lens indicated that predicted RE was significantly smaller with the segmental method (0.45 ± 0.86 D) than that with the composite method (0.80 ± 0.86 D, P < 0.001). Segmented AL with SS-OCT is more accurate than composite AL in eyes with extremely long AL and can improve post-operative hyperopic shifts in such eyes.