100-degree non-contact visible-light OCT and SLO for in vivo mouse retinal imaging

The mouse model plays a pivotal role in ophthalmic and neuroscience research. In particular, transgenic mouse strains enable in-depth investigation into physiological processes such as microglia activation, one of the events before retinal vasculopathy, ganglion cell death, or nerve fiber loss [1]. To better visualize changes associated with neuron disorders and vascular alterations in the development of retinal diseases, non-invasive imaging modalities are desirable. Among them, OCT and SLO have been widely used to characterize retinal structure and function in vivo [2]. While OCT performs three-dimensional imaging of structure and vasculature, SLO can achieve endogenous and exogenous fluorescence imaging with a resolution down to the single-cell level. In our prior work, we have demonstrated a multimodal vis-OCT and SLO system with a 34° (visual angle) field of view (FOV), successfully capturing retinal structure, vasculature, and fluorescently labeled microglia in healthy mice [3]. However, the FOV remains relatively narrow, which restricts the application in retinal diseases that affect peripheral regions, such as retinopathy of prematurity. Moreover, most reported OCT and SLO systems for mouse retinal imaging also have a limited FOV (approximately 50°, visual angle) [4,5], which potentially misses critical peripheral pathology. Here, we describe a non-contact vis-OCT and SLO system with a 100° FOV (visual angle) and demonstrate the performance in transgenic mice with Enhanced Green Fluorescent Protein (EGFP)-labeled microglia.