Abstract
Purpose :
This study seeks to elucidate the cellular identity of the hyperreflective dots imaged by visible light optical coherence tomography (vis-OCT) within 24 hours following the optic nerve crush injury.
Methods :
Adult wild-type C57BL/6 mice and CX3CR1GFP/GFP mice were used for in vivo vis-OCT tracking and ex vivo confocal imaging. Vis-OCT imaging of the mouse retina and vitreous body were performed before and at 12 hours, 1 day, 3 days, 6 days, and 12 days after optic nerve crush (ONC) surgery. Crushed and uncrushed eyes also underwent whole eye sagittal sectioning, immunostainings by retinal and inflammatory markers, followed by confocal imaging and data analysis for identification of cell types.
Results :
We found that the peak of the vitreous hyperreflective dots occurred within the first day after ONC and decreased over time. These signals concentrated near the optic nerve head (ONH) and progressively spread outward to the peripheral regions. Confocal images of whole eye sagittal sections showed that CX3CR1-GFP+ cells, which are microglia or macrophages, also increased in the vitreous and the retina at 1-day post ONC. A significant proportion of GFP+ cells in the vitreous were also double-immunolabeled for ionized calcium binding adaptor molecule 1 (Iba1) and Transmembrane Protein 119 (Tmem119), markers for retinal microglial cells.
Conclusions :
Our study showed that the inflammatory signals occurs within 24 hours post ONC, and they are possibly retinal microglia. Our results build the foundation to examine the molecular mechanisms underlying the early retinal damage which is important for early prediction and timely intervention of retinal ganglion cell degeneration and subsequent vision loss.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.