Analysis of vitreous immunity using OCT in rats with steroid‐induced glaucoma

Purpose: The subclinical immune response mediates a homeostatic role in healthy situations, but in pathological situations it misbalances. Glaucoma is a multifactorial pathology in which immunity is involved. Optical coherence tomography (OCT) detects the immune response in vitreous as hyperreflective opacities. The aim of this study is to monitor vitreous parainflammation in two steroid induced glaucoma (SIG) animal models, comparing both sexes and healthy controls over 6 months. Methods: Two SIG models were induced by injecting a suspension of PLGA‐Ms loaded with dexamethasone or dexamethasone/fibronectine into the anterior chamber of rat eyes. Intraocular pressure (IOP) was measured by rebound tonometer every week and vitreous‐retinal interface was evaluated with OCT at 0, 4, 8, 12, 18 and 24 weeks of follow‐up. Vitreous images were exported as AVI videos and then we designed a computational analysis that characterizes and classifies the vitreous hyperreflective opacities based on their size into isolated cells (10 microns 2 ), non‐activated cells (10–50 microns 2 ), activated cells (50–250 microns 2 ) and complexes (>250 microns 2 ). Vitreous/retinal pigment epithelium (VIT/RPE) relative intensity, opacity/cell intensity, eccentricity and orientation were analysed. Results: SIG eyes showed tendency of greater intensity, and number of vitreous opacities ( p < 0.05) with dynamic fluctuations. Both SIG models showed an antinflammatory profile, with non‐activated cells as the highest population over the study. However, smaller opacities (isolated cells) seems to be the first responder to noxa since they were the most rounded (recruitment) coinciding with IOP peak increase, showed the highest mean intensity (intracellular machinery) even in contralateral eye, and the greatest change in orientation (motility). Conclusions: Study the features of hyper‐reflective opacities in vitreous using OCT could be a biomarker of glaucoma onset and progression.