Same-session dual chromophore riboflavin/UV-A and rose bengal/green light PACK-CXL in Acanthamoeba keratitis: a case report

Background: Acanthamoeba keratitis (AK) is the most challenging corneal infection to treat, with conventional therapies often proving ineffective. While photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) with riboflavin/UV-A has shown success in treating bacterial and fungal keratitis, and PACK-CXL with rose bengal/green light has demonstrated promise in fungal keratitis, neither approach has been shown to effectively eradicate AK. This case study explores a novel combined same-session treatment approach using both riboflavin/UV-A and rose bengal/green light in a single procedure.

Case presentation: A 44-year-old patient with active AK in the left cornea, unresponsive to 10 months of conventional treatment according to American Academy of Ophthalmology (AAO) guidelines, was treated using same-session sequential PACK-CXL with riboflavin/UV-A (365 nm) irradiation (10 J/cm²) and rose bengal/green light (522 nm) irradiation (5.4 J/cm²) in a single setting. The procedure was repeated twice due to persistent signs of inflammation and infection. After three combined same-session PACK-CXL treatments, the patient's cornea converted to a quiescent scar, and symptoms of ocular pain, photophobia, epiphora, and blepharospasm resolved. Confocal microscopy revealed no detectable Acanthamoeba cysts. The patient currently awaits penetrating keratoplasty.

Conclusions: The same-session combination of riboflavin/UV-A and rose bengal/green light PACK-CXL effectively treated a patient with confirmed AK that was resistant to conventional medical therapy, suggesting that using two chromophores in a single procedure may represent a future treatment alternative for AK.