Analysis of vitreous by optical coherence tomography as biomarker in neurodegenerative diseases

Abstract

Purpose: Neurodegeneration is multifactorial and the immune factor is key. Chronic and acute inflammation can be analysed as hyperreflective opacities in the vitreous (HOV) by optical coherence tomography (OCT) imaging. This study analyzes vitreous cellularity by OCT in two neurodegenerative diseases, chronic glaucoma (CG) and relapsing remitting multiple sclerosis (RRMS) compared to healthy individuals.Methods: Four models of CG generated in rats by episcleral veins sclerosis (EVS n = 35) or injection of biodegradable microspheres into the anterior chamber of the eye non‐loaded (Ms n = 28) and loaded with dexamethasone (Dex n = 43) and Dex‐fibronectin (DexFibro n = 44), compared to healthy rats (n = 32). In addition, patients with RRMS treated (n = 20) and healthy subjects (n = 20) were analysed. The relative intensity of vitreous/retinal pigment epithelium (VIT/RPE) obtained from OCT (for animal and human use) images was quantified. A custom program computational analysis characterizes in vivo the HOV (number and size), identified histologically as hyalocyte‐like Iba‐1+ (microglial marker) cells in animals. For humans, artificial intelligence methods and Image J software were used.Results: Both image analysis techniques identified HOV in animals with chronic glaucoma, in patients with RRMS and in healthy (both animals and humans). Chronic glaucoma models presented more HOV than healthy (decreasing from 100 ‐EVS‐ to 15 ‐healthy‐) (p < 0.05). Corticosteroid models presented an anti‐inflammatory profile (with non‐activated cells as the highest population). However, according VIT/RPE intensity, patients with RRMS treated did not show differences vs. healthy humans (p > 0.44).Conclusions: HOV analysed by OCT were identified in neurodegenerative diseases of chronic course, in outbreaks, and healthy individuals. The presence of anti‐inflammatory drugs (dexamethasone in animals) and immunemodulators (in humans) decreased the VIT/RPE intensity resembling healthy conditions.Acknowledgments: Grants MAT2017‐83858‐C2‐1 and MAT2017‐83858‐C2‐2 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. Grants PID2020‐113281RB‐C21 and PID2020‐113281RB‐C22 funded by MCIN/AEI/ 10.13039/501100011033. Research Group UCM920415 (InnOftal). MJR thanks for the grants M17/00213 and JR22_00057.