Examining murine eye length asymmetry with spectral domain optical coherence tomography

The mouse is an increasingly popular model for examining refractive development, however measuring axial length in the small mouse eye is challenging. We measured ocular axial dimensions with spectral domain optical coherence tomography (SD-OCT) and examined how ocular dimensions vary with alignment of the SD-OCT system in a mouse model of lens-induced myopia. Refractive error, corneal radius of curvature, and ocular dimensions were measured in C57BL/6J mice from P25 to P46. Mice received monocular lens treatment with either a -10D (n = 14) or -30D lens (n = 13) at P28 or had no lens treatment (n = 14). OCT images were taken at different eccentricities in the temporal, nasal, inferior, and superior quadrants of the eye. Axial length, vitreous chamber depth (VCD), and anterior chamber depth decreased with increasing eccentricity (P < 0.001), whereas lens thickness increased with greater eccentricity (P < 0.001). Axial length and VCD were longer in the superior and temporal quadrants compared to the nasal and inferior quadrants (P < 0.001). The -30D lens induced a greater myopic shift compared to the -10D lens (P < 0.001). Both lenses induced a steeper corneal curvature compared to the contralateral eye (P < 0.01). There were no significant differences in ocular dimensions between lens treatment groups, quadrants, or eccentricities (P > 0.05). Changes in corneal radius of curvature could predict the myopic shift observed with lens treatment. Findings suggest that there are significant differences in axial length measurements depending on the alignment of the OCT system. Thus, consistent alignment to the same region is important for accurate comparison of axial length in mouse eyes with experimental myopia.