Abstract
Purpose :
Spectral domain optical coherence tomography (SD-OCT) is frequently used to measure axial length in mouse models of myopia. However, the small size of the mouse eye can make it challenging to detect differences in axial length due to myopic eye growth. Here, we examined how the alignment of the OCT affects ocular axial measurements in the mouse eye.
Methods :
C57BL/6J mice (male, n=9) were imaged with SD-OCT at postnatal day 29 (Leica Bioptigen 4300). Alignment of the OCT image was adjusted by rotating the mouse platform so that images of whole mouse eyes were taken at 4-, 8-, and 12-degrees eccentricity in the temporal, nasal, inferior, and superior quadrants with respect to the optic nerve head (ONH). Corneal thickness (CT), anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), retinal thickness (RT), and axial length (AL) were quantified. Two-way repeated measures ANOVA was used to compare ocular parameters between quadrants and eccentricities.
Results :
CT did not significantly differ based on quadrant or eccentricity (P>0.05). ACD, VCD, and AL were 1.0%, 3.2%, and 0.6% longer, respectively, in the temporal compared to the nasal quadrant (P<0.05). VCD was also 3.6% and AL was 0.6% longer in the temporal compared to the inferior quadrant (P<0.01). As expected, ACD and VCD significantly decreased with increasing degrees from the ONH (percentage change between 4- and 12-degrees: -1.2% and -5.9% for ACD and VCD, respectively; P<0.01), whereas LT and RT significantly increased with increasing degrees (+0.5% and +11.7%, respectively; P<0.05). AL deviated from these trends with length decreasing with increasing degrees in the nasal and superior quadrants (-0.6% for both; P<0.01) but were similar at 8- and 12-degrees in the temporal (P=0.41) and inferior quadrants (P=0.13).
Conclusions :
Axial length and other ocular parameters varied depending on the alignment of the OCT. Axial length was most variable across eccentricities in the superior quadrant and less variable in the temporal and inferior quadrants. Variability in the alignment of the OCT image may contribute to challenges in detecting changes in axial length in mouse eyes. Findings suggest that alignment to the temporal or inferior quadrants may provide better measurement consistency compared to the nasal or superior quadrants.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.