Multiple Sterile Corneal Infiltrate After Crosslinking Procedure In Patient With Keratoconus

To describe a case of corneal sterile infiltrate after crosslinking procedure (CXL) in a patient with keratoconus. CXL is a safe procedure with few complications described, and sterile infiltrates are among the rarest. This is a challenging condition due to a marked reduction in visual acuity and the differential diagnosis with infectious keratitis. The treatment differs a lot between these entities and the fear of worsening may delay specific treatment for sterile infiltrates. In this particular case, we highlight the large number of lesions and their increased extent when compared with previous reports in the literature. Consent form was signed by the patient and the study was approved by the local research ethics committee.

This study was conducted (including patient surgery, follow up and exams) in the cornea division of Suel Abujamra Institute, a secondary care and teaching hospital dedicated exclusively for Ophthalmology, and in cornea division of São Paulo Hospital, Federal University of São Paulo, a tertiary hospital. Both are located in São Paulo, São Paulo State, Brazil. The follow up took place between August 2024 and February 2025.

A 23-year-old male patient diagnosed with keratoconus (KC), with no other ocular or systemic pathologies, presented with disease progression and uncorrected visual acuity (UCVA) of 20/60 in the right eye (OD). He was submitted to CXL according to the Dresden protocol. Ketorolac tromethamine 0.5% four times a day for two days, moxifloxacin 0.5% four times a day and prednisolone acetate 1% (PA1%) six times a day were prescribed. First day post operatory (PO) evaluation was unremarkable. He returned after seven days with irregular use of eye drops and reporting worsening of visual acuity. UCVA was 20/400, and biomicroscopy showed 1+/4 conjunctival hyperemia, cornea with multiple areas of subepithelial infiltrate and anterior stromal opacities, distributed in the mid-periphery and periphery, with a lucid interval in relation to the limbus. Three lesions presented with a central epithelial defect smaller than the infiltrate. The hypothesis of infectious keratitis was raised, therefore increased Moxifloxacin 0.5% to eight times a day and reduced (PA1%) to twice a day. The patient returned after 48 hours with corneal scraping and confocal microscopy negative, presenting reduction of epithelial defect. The hypothesis changed to sterile corneal infiltrates, and the therapeutic regimen changed with suspension of Moxifloxacin 0.5% and increasing the frequency of (PA1%) to eight times a day. With the treatment, there was a partial improvement in the lesions and in the UCVA to 20/80.

Sterile infiltrate is a possible early complication after CXL, therefore patients should be closely and carefully evaluated after the procedure. Risk factors like blepharitis, non-steroidal anti-inflammatory drugs use and punctate keratitis should be monitored before the surgery. In the presence of any infiltrate after CXL, it is fundamental to exclude infectious causes before prescribing anti inflammatory treatment. Further studies are necessary to determine the pathophysiology and to allow an early differentiation between this condition and infectious keratitis.