Sterile Corneal Infiltrate: A Difficult Dilemma

Corneal infiltrate is a common presentation in ophthalmic emergency departments. Infiltrates can be classified as sterile or infectious. Sterile corneal infiltrate (SCI) is less studied compared to infectious infiltrate. SCI can present in individuals who wear contact lenses or after corneal procedures, such as corneal collagen cross-linking (CXL), photorefractive keratectomy (PRK), and laser-assisted in situ keratomileusis (LASIK). It is crucial to distinguish between SCI and infectious keratitis, as the treatment approach differs greatly. Infectious infiltrates often present with mucopurulent discharge, significant pain, and photophobia. Generally, corneal infiltrates with an intact epithelial layer are mostly sterile, while infectious cases usually have epithelial defects. Infectious infiltrates are typically larger than SCIs. Furthermore, central corneal involvement, anterior chamber reaction, and hypopyon tend to support an infectious etiology. Even experienced cornea specialists struggle to accurately differentiate between sterile and infectious infiltrates. Except for highly suggestive cases of SCI, corneal scraping before treatment seems logical. The mainstay of SCI treatment is topical corticosteroids. Nevertheless, it is strongly recommended to concurrently administer topical antibiotics in the therapeutic regimen. Those patients on corticosteroids with a compromised immune system might be prone to fungal infections. Thus, apart from prophylactic antibiotics, thorough and close follow-up visits to assess infiltration is crucial.