Chronic effects of EKC
EKC may lead to chronic and sometimes irreversible corneal and conjunctival disease in the post infection phase. . These include post infectious dry eye syndrome due to the loss of goblet cells, conjunctival micro scarring, irregular astigmatism, corneal scars, recurrent corneal erosions, and other long term sequelae. Post capsular cataracts are a known complication of long term steroid use often necessitated in chronic cases of EKC.
Any cytopathogenic agents infecting the ocular surface, including the adenovirus, result in a post infectious dry eye syndrome due to the loss of goblet cells. This event is clinically relevant in about one third of patients. This may sometimes be difficult to differentiate from an ongoing infection. The differential diagnosis can be made utilizing tests such as Schirmer’s, Bengal rose stain, break-up time, tear film interference, and impression cytology.
Rarely, (sub)epithelial conjunctival scars can develop particularly in patients that had experienced fulminant and pseudomembraneous disease and lead to persisting corneal irritation and pain sensation [Fig. 9]. Also, as a sequel to the more serious dry eye syndromes with persistent infection and ongoing inflammation, mild symblephara can result.
The clinical symptoms of EKC and AHC are generally self-limiting after 2–3 weeks respectively 4–6 days, However, even after 2 years nummular corneal lesions (and a decrease in vision from 1.0 to 0.5) can be biomicroscopically documented for HAdV8 infections in 47% of patients.30 Adenovirus can be isolated from the conjunctiva of a cohort of patients in a decreasing time pattern – about 50% of patients after 10 days are still infective, some remain infective for more than 2 years. In case of AHC, HAdV2, HAdV3, HAdV4, HAdV5, HAdV19 can also be isolated even several months after onset.EKC is most common during the fall and winter and, in contrast to PCF, presents unilaterally in two-thirds of cases and doesn’t cause fever or sore throat. Keratitis occurs in ap–proximately 80 percent of patients with associated discomfort, photophobia, tearing and mild blepharospasm. Following redness and keratitis, up to 20 uniform, subepithelial corneal infiltrates (the hallmark of EKC) develop on day 11 and are most prevalent during the third and fourth weeks of infection. Approximately 30 to 50 percent of patients with EKC will develop these infiltrates, which may contribute to persistent visual loss and light sensitivity and necessitate long-term steroid therapy. The infiltrates are a product of the immune response to the keratitis and are smaller, more numerous, denser, produce greater photophobia and last longer (up to a year) than PCF infiltrates.In addition, EKC may lead to persistent dry eye or conjunctival scarring.1 – See more at: Review of Ophthalmology® > A guide to understanding adenovirus, the diseases it causes and the best ways to treat these conditions.