Abstract
Purpose :
Visible-light optical coherence tomography (vis-OCT) provides high axial resolution and unique backscattering information compared with conventional OCT. However, vis-OCT signal quality is lower in young mice, chiefly due to attenuating hyaloid vessels that persist for several weeks after birth, potentially preventing the use of vis-OCT in mouse models of pediatric eye diseases. We explore the feasibility of using vis-OCT to track developmental changes in the murine inner retinal structure in vivo, starting at eye-opening.
Methods :
Wildtype C57BL/6 mice from P12 to P60 were separated into four age groups: 1) P13-P16,right after eye-opening, 2) P18-21, 3) P24-31, and 4) P40-P60 (mature). We acquired vis-OCT images centered on the optic nerve head with a field-of-view of 1.1 mm × 1.1 mm. We utilized a resampled circular B-scan averaging technique in post-processing to improve inter-layer retinal contrast (example resampled circular B-scan shown in Figure a). Histology images were acquired via confocal microscopy. For both vis-OCT and histology data, we measured the thickness of the retinal nerve fiber layer + ganglion cell layer (RNFL/GCL), inner plexiform layer (IPL), inner nuclear layer (INL), and total retina using ImageJ. Figure b is a magnified view of the orange box from Figure a with relevant layers used for measurements labelled. All measurements were taken 300-550 µm from the optic nerve head.
Results :
We averaged nine acquisitions and developed a resampled circular B-scan method, which enabled repeatable retinal layer thickness measurements from vis-OCT datasets in all age groups. The correlation constant between OCT and histology, defined as the ratio of the OCT thickness measurement to the histology thickness measurement, ranged from 0.68 to 1.18 across the different retinal layers and age groups. These results are consistent with previously published values of correlation constant in healthy adult mice. The correlation coefficient between OCT and histology, defined as Pearson’s correlation coefficient (R2) for the line of best fit under a preassumed linear relationship between OCT and histology layer thickness measurements, is 0.996.
Conclusions :
Vis-OCT retinal layer thickness measurements agreed well with histology for all layers and age groups examined. Vis-OCT can visualize and track developmental changes in the murine retinal layer structure in vivo from eye-opening.
This is a 2021 ARVO Annual Meeting abstract.