# Patterns of Inflammation in Experimental Autoimmune Uveitis and Their Correlation to Optical Coherence Tomography Findings in Human Uveitis

## TL;DR

This study connects OCT imaging in human uveitis with rat models to better understand inflammation patterns and tissue damage.

## Contribution

It correlates human OCT findings with rat EAU histology to reveal inflammation mechanisms.

## Key findings

- Hyperreflective OCT signals correspond to lymphocyte infiltration in rat EAU models.
- Lymphocyte and macrophage infiltration occurs through retinal vessels and pigment epithelium.
- Comparing OCT and histology improves understanding of uveitis immunopathogenesis.

## Abstract

Experimental autoimmune uveitis (EAU) in rats is a pivotal model for understanding the immunological mechanisms of human uveitis and developing therapies. In humans, optical coherence tomography (OCT) allows for the in vivo detection of characteristic findings in active uveitis, as well as sequelae of inflammation. The objective of this study was to correlate OCT findings in patients with uveitis with retinal histologies from two rat models of EAU caused by T cells with different autoantigen specificities and well-known underlying immunological pathomechanisms. Patients with various noninfectious uveitis subtypes underwent imaging using an ultra-widefield swept source or conventional OCT. Histological cryosections from rat eyes with experimental autoimmune uveitis were stained for T cell and/or macrophage markers. Typical human OCT findings were reproduced in the experimental animal model. Hyperreflective signals observed on OCT corresponded to lymphocyte infiltration in histological sections. This infiltration was typically found as vasculitis in the perivascular regions and snowballs in the posterior hyaloid. There was lymphocyte and macrophage infiltration of the retina through the retinal vessels and the retinal pigment epithelium. Comparing in vivo OCT imaging of human uveitis with corresponding histologies from rat models improves our understanding of the type of inflammation, extent of tissue destruction, and immunopathogenesis.