Abstract
Purpose: :
To determine and compare the precision and accuracy of in vivo axial length measurements of murine eyes using 780nm partial coherence interferometry (PCI) and 1310nm spectral domain optical coherence tomography (SD-OCT) techniques.
Methods: :
Axial lengths (AL) were measured in vivo at postnatal day (p) 58 in C57BL/6J mice with 780nm custom-made PCI and 1310nm SD-OCT (Bioptigen). Matching data sets were collected by different users with PCI and SD-OCT at p58 to assess inter-user variability. Also, repeated measurements of the same mice were collected by different users at p58 to assess intra-user variability. Collected data were analyzed for precision and accuracy using the Bland-Altman coefficient of repeatability (CR), Bland-Altman agreement plots, and intra-class correlation (ICC) coefficients. To investigate the effects of misalignment, additional SD-OCT measurements were collected by displacing the eye position two-degrees along the nasal-temporal and superior-inferior axes.
Results: :
Axial length measurements were 3.274 ± 0.046 mm for PCI and 3.292 ± 0.041 mm for OCT (mean ± SD, n= 5). ICC coefficient for PCI and SD-OCT was 0.98, indicating a high correlation between two instruments. Inter-user ICC coefficients for PCI and OCT were 0.95 and 0.96, respectively. Intra-user ICC coefficients values for PCI and OCT were 0.99 and 1.0, respectively, indicating negligible measurement differences between and within users. In SD-OCT, a maximal change of AL 0.06% when misaligned along the nasal-temporal axis and 0.89% when misaligned along the superior-inferior axis.
Conclusions: :
PCI and SD-OCT measurements correlate well for AL measurements. High precision and accuracy of both instruments were confirmed by high inter and intra-user repeatability ICC coefficients. Careful alignment of the mouse along the superior-inferior axis is critical for precise and accurate AL measurements.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • myopia • refractive error development