Abstract
Purpose :
Glaucomatous optic neuropathy is associated with axonal damage and blindness. Optical coherence tomography (OCT) has been used to assess progressive retinal nerve fiber layer (NFL) structural changes in the peripapillary region consistent with optic nerve (ON) damage. We have previously developed a diffusion basis spectrum imaging (DBSI) to assess ON axonal damage and cellularity. In this study, we correlate OCT assessed retinal layer thickness with DBSI assessed axon/myelin injury, axon loss and inflammation in ON crush (ONC) mice.
Methods :
Spectral domain OCT cross-sectional imaging of the peripapillary region was performed with measurement of the retinal ganglion cell (RGC)/NFL thickness prior to and at Day 7 post-ONC procedure. Five C57BL/6 mice underwent ONC (left eye) using 45-degree-bent micro-forceps at the location approximately 1-2 mm from the eyeball for 20s. Right eye served as control (CTL). Optic nerve DBSI was performed on a 4.7-T Agilent small-animal MR scanner using a 25-direction diffusion-weighting scheme.
Results :
RGC/NFL thickness assessed at ONC retina at Day 7 was significantly decreased (15.4 μm ± 1.3) compared to baseline (17.5 μm ± 1.3, p<0.01), correlating with DBSI λ‖ (axonal injury), DBSI λ⊥ (demyelination), DBSI-derived axon loss, and cellularity (inflammation) in ONC nerves.
Conclusions :
OCT detected retinal NFL thinning in ONC eyes associated with ON axonal injury, axon loss, and inflammation. More animal number and corresponding histological markers for ON are currently being pursued to quantitatively validate the correlation between OCT and DBSI measurements.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.