From mild cases of punctate epithelial erosions or keratopathy to severe subepithelial corneal infiltrates, infectious conjunctivitis can lead to vision loss when the cornea becomes inflamed. While it is unclear whether preventive treatment can stop corneal sequelae in infectious conjunctivitis, a recent study aimed to find biomarkers that may help answer that question.

The researchers identified apolipoprotein E (APOE) as a biomarker for corneal involvement in patients with acute infectious conjunctivitis in India and Thailand. The study, published in JAMA Ophthalmology, analyzed conjunctival swabs from patients with infectious conjunctivitis, focusing on the presence of corneal involvement. The researchers employed differential gene expression analysis and predictive algorithms that identified APOE as a significant marker. The study was conducted in three phases, involving 58 samples for model training and validation, and an additional cohort from the SCORPIO study for further validation.

APOE expression was significantly higher in patients with corneal involvement compared with those without. The logistic regression model also showed that removing APOE from the gene set resulted in decreased predictive performance, which further points to APOE as a meaningful conjunctival marker. In India, the model demonstrated 56% sensitivity and 88% specificity in classifying corneal involvement with APOE. Results were similar for Thai patients.

“Given that a careful slitlamp examination can reveal corneal pathology, the utility of a biomarker associated with corneal pathology is helpful in a few settings,” the researchers say. “One is when a careful slitlamp eye examination is not available, particularly in resource-poor areas or when a patient presents to primary care or an emergency department lacking in ophthalmology services.” Because most patients with conjunctivitis present to primary care rather than ophthalmologists, a point-of-care test for APOE could be useful in making referrals for specialized care. Cost of treatment may also be positively affected with such a point-of-care test as the number of follow-up visits needed decreases.

The investigators suggest further research into APOE’s correlations with clinical severity, ability to predict disease, and effects on clinical management. “If APOE can predict the development of keratitis early in the conjunctivitis course, the potential for earlier or preventive measures can be initiated,” they conclude.