Histomorphological Changes in Experimental Autoimmune Uveitis of Varying Severity

Aim: to evaluate the histomorphology of the eyes of rabbits with experimental autoimmune uveitis (EAU) of varying severity.
Materials and Methods: The study was conducted on 30 Chinchilla rabbits with EAU, which were divided into two groups according to the severity of the disease. Histomorphological examination of the rabbit eyes was performed.
Results: In general, the inflammatory process can be characterized as a humoral-type hypersensitivity reaction. An inflammatory process was observed, predominantly affecting the inner ocular layers – mainly the choroid and retina. Inflammatory changes in the iris were sporadic, minimal, and primarily consisted of a few scattered lymphocyte-like cells. In the ciliary body, inflammation predominantly involved the ciliary processes. Damage to the retinal pigment epithelium was predominantly observed in the optical part. The involvement of the choroidal vasculature was evident, accompanied by stromal exudation. Retinal alterations predominantly involved the inner layers.
The bipolar and ganglion cell layers were essentially destroyed, while the photoreceptor layer was largely preserved. Destruction of the retinal pigment epithelium was associated with damage to Bruch’s membrane.
Conclusion: Overall, histomorphological alterations in EAU showed a time-dependent progression, peaking between Days 3 and 10, particularly in moderate and severe cases. Although inflammatory activity decreased from Day 14 onward, complete morphological recovery was not observed. Persistent intergroup differences indicate sustained, partially irreversible ocular tissue damage associated with disease severity.