Noninfectious ring-shaped keratitis associated with Pseudomonas aeruginosa

Area of Science:

• Ophthalmology
• Microbiology
• Immunology

Background:

• Soft contact lens wear is a significant risk factor for microbial keratitis.
• Corneal abrasions can serve as entry points for pathogens or their toxins.

Observation:

• A 37-year-old woman developed a ring-shaped keratitis in her left eye after five years of soft contact lens use.
• The condition appeared within seven days of a central corneal abrasion.
• Gram staining and cultures identified Pseudomonas aeruginosa in her contact lens and cleaning solution.

Findings:

• Despite the presence of Pseudomonas aeruginosa, there was no clinical or laboratory evidence of a true infectious process.
• The ring formation is hypothesized to be caused by P. aeruginosa endotoxin entering the corneal stroma through the abrasion.
• This may trigger an antibody-independent complement activation pathway.

Implications:

• This case suggests that sterile ring infiltrates in contact lens wearers can be associated with bacterial endotoxins.
• Early diagnosis and prompt treatment with antibiotics and anti-inflammatory agents are crucial for visual recovery.
• Understanding the non-infectious inflammatory mechanisms is important for managing contact lens-related complications.