Ocular manifestations of viral diseases

Viral infections may involve all ocular tissues and may have short and long-term sight-threatening consequences. Among them, ocular infections caused by herpesviruses are the most frequent. HSV-1 keratitis and kerato-uveitis affect approximately are the leading cause of infectious blindness in the Western world, mainly because of corneal opacification caused by recurrences. For this reason, they may warrant long-term antiviral prophylaxis. Herpes zoster ophthalmicus, accounts for 10 to 20% of all shingles locations and can be associated with severe ocular involvement (keratitis, kerato-uveitis) of which a quarter becomes chronic/recurrent. Post herpetic neuralgias in the trigeminal territory can be particularly debilitating. Necrotizing retinitis caused by herpesviruses (HSV, VZV, CMV) are seldom, but must be considered as absolute visual emergencies, requiring urgent intravenous and intravitreal antiviral treatment. Clinical pictures depend on the immune status of the host. Adenovirus are the most frequent cause of infectious conjunctivitis. These most often benign infections are highly contagious and may be complicated by visually disabling corneal lesions that may last over months or years. Some arboviruses may be associated with inflammatory ocular manifestations. Among them, congenital Zika infections may cause macular or optic atrophy. Conjunctivitis is frequent during the acute phase of Ebola virus disease. Up to 15% of survivors present with severe chronic inflammatory ocular conditions caused by viral persistence in uveal tissues. Finally, COVID-19-associated conjunctivitis can precede systemic disease, or even be the unique manifestation of the disease. Utmost caution must be taken because of viral shedding in tears.