# Comparison of Eye Axial Length Measurements Taken Using Partial Coherence Interferometry and OCT Biometry

## TL;DR

This study compares two methods for measuring eye length and finds they are mostly interchangeable but should be used carefully for tracking changes over time.

## Contribution

The study provides evidence for the interchangeability of OCT and PCI in axial length measurements, with implications for myopia management.

## Key findings

- There is a near-zero and non-significant bias between PCI and SD-OCT measurements.
- The 95% limits of agreement between the two methods are 0.06 mm.
- Both devices can accurately measure axial length, but caution is needed for longitudinal comparisons.

## Abstract

This study evaluates the inter-device measurement properties of partial coherence interferometry (PCI) and spectral domain optical coherence tomography (SD-OCT) in measuring axial length, particularly for myopia management. We recruited 82 eyes from 41 adult participants with a mean age of 31.0 ± 17.6 years and a mean spherical equivalent of −2.20 ± 2.28 D. Axial length was measured using SD-OCT and PCI for both the right and left eyes. Agreement between the two measurements was assessed using Bland–Altman analysis, and graphs and values were compared with linear mixed models. The results show a near-to-zero and non-significant bias between measurements. The 95% limits of agreement showed a value of 0.06 mm. Both devices can accurately measure the axial length. OCT biometry performed with SD-OCT can be successfully interchanged with partial coherence interferometry, but they should be cautiously interchanged when performing longitudinal comparisons.