AOA 2026: Identifying and tackling rare corneal infiltrates

Joe Shovlin, OD, FAAO, of Northeastern Eye Institute in Scranton, Pennsylvania, part of Vision Innovation Partners, discussed key points from his lecture on rare corneal infiltrates—“uninvited guests of the cornea”—with emphasis on infectious keratitis in contact lens wearers and when to refer to a specialist.

Shovlin explained that a major challenge in managing corneal infiltrates is diagnostic confusion among multiple pathogens, particularly in contact lens users. Bacterial vs fungal infiltrates can be difficult to distinguish clinically, and acanthamoeba keratitis may be misdiagnosed as herpes simplex keratitis. He noted that acanthamoeba often presents with reduced corneal sensation early on, rather than increased pain, until later stages when scleritis or more severe disease develops. Shovlin also described characteristic appearances: streptococcal infections can produce filamentous, spicule-like infiltrates due to dextrin deposition in the cornea, mimicking fungal patterns; Mycobacterium may show a wispy phenotype; and MRSA/MRSE infiltrates can appear different from more conventional Staphylococcal or Streptococcal infections.

Shovlin underscored the prognostic importance of early, accurate diagnosis, particularly in fungal disease. High intraocular pressure, the presence of a tubercle, and involvement near the limbus (within 2 mm) signal a worse prognosis and an increased risk of endophthalmitis; such cases may warrant grafting. While he believes that most cases of infectious keratitis can be managed by a capable optometrist, Shovlin stressed that rare infections—notably acanthamoeba and some fungal keratitides—are best handled by a corneal specialist familiar with appropriate therapies and drug access.

Shovelin outlined red flags that should prompt urgent referral or more intensive workup: organic trauma, deep stromal involvement, scleral extension, and nosocomial infections, all of which should be cultured. In terms of prevention, he highlights contact lens hygiene and compliance—adhering to wearing schedules, using appropriate solutions, and avoiding any water exposure, especially swimming with lenses or wearing them in potentially contaminated environments, such as during or after hurricane-related disruptions.

Finally, he recommends a 5-day rule: if a presumed infection does not respond to seemingly appropriate therapy within about five days, clinicians should rethink the diagnosis, consider alternative etiologies (eg, fungal instead of bacterial, or acanthamoeba instead of herpes simplex), and possibly re-culture and/or refer. Throughout, he emphasized that vigilance, early recognition, and timely referral are key to optimizing visual outcomes in these complex corneal infections.