Eales' Disease: When the Rare Sounds Frequent

Double Trouble: Eales Disease in a Background of Paradoxical Embolism

Eales disease is an idiopathic retinal vasculitis that mainly affects the periphery of the retina. The disease commonly manifests as peripheral retinal perivasculitis, peripheral retinal capillary nonperfusion, neovascularization, and recurrent vitreous hemorrhage. Here, we present the case of a 36-year-old male who was diagnosed with Eales disease after presenting with sudden onset flashes of light, reduced visual acuity, and a black spot in his left eye. Upon examination, his left eye exhibited a superior non-foveal branch retinal artery occlusion (BRAO) with a sludged blood column, an old extramacular branch retinal vein occlusion (BRVO) with hemorrhage, and vascular sheathing. Initial laboratory investigations, including antibody testing for causes of retinal ischemia and stroke workup, were negative. Later, the patient presented with a BRAO in the right eye and a cerebral infarction shortly thereafter, further complicating his clinical picture. A diagnosis of Eales disease was made based on the evolution of retinal findings showing peripheral non-perfusion, vascular sheathing, collateral formation, neovascularization with leakage, absence of additional BRAOs following repair of his patent foramen ovale, and lack of other explanatory conditions. The initiation of systemic corticosteroids resulted in the improvement and stabilization of his vision. This case highlights the challenges in diagnosing Eales disease, underscoring the importance of timely identification for the appropriate management and prevention of vision loss.

Immune Privilege Furnishes a Niche for Latent Infection

The microenvironment of the CNS (eye and brain) is fertile ground for infection if the barriers are breached. The result of pathogen invasion is often devastating destruction of tissues. In the eye, inflammation is broadly classified either as "infectious" (i.e. caused by infection) or "non-infectious". However, increasingly, forms of intraocular inflammation (IOI), which clinically appear to be "non-infectious" turn out to be initiated by infectious agents, suggesting that pathogens have been retained in latent or persistent form within ocular tissues and have reactivated to cause overt disease. A similar pathogenesis applies to latent infections in the brain. Not all CNS tissues provide an equally protective niche while different pathogens escape detection using different strategies. This review summarises how immune privilege (IP) in the CNS may be permissive for latent infection and allow the eye and the brain to act as a reservoir of pathogens which often remain undetected for the lifetime of the host but in states of immune deficiency may be activated to cause sight- and life-threatening inflammation.