Peripheral ulcerative keratitis in rheumatoid arthritis patients taking tocilizumab: Paradoxical manifestation or insufficient efficacy?

Objectives. Peripheral ulcerative keratitis (PUK) is a severe corneal condition associated with uncontrolled RA. Tocilizumab (TCZ) is used to control RA, however, episodes of paradoxical ocular inflammation have been reported in TCZ-treated patients. We report a case series of PUK in TCZ-treated RA patients with ophthalmological and systemic findings and discuss the potential underlying mechanisms. Methods. Four patients (six eyes), 47-62 years of age, were included. At the onset of PUK, the median duration of RA was 13 years [interquartile range (IQR) 3-13] and the median treatment with TCZ was 9 months (IQR 3-14). Two patients had active disease [28-joint DAS (DAS28) >3.2] and the disease was controlled in two patients (DAS28 ≤3.2). Results. TCZ was initially replaced by another immunomodulatory treatment in all patients and later reintroduced in two patients without PUK recurrence. Corneal inflammation was controlled in all cases with local and systemic treatments, with severe visual loss in one eye. Conclusion. PUK may occur in patients with long-standing RA after a switch to TCZ and can be interpreted, depending on the context, as insufficient efficacy or a paradoxical manifestation. These cases highlight the urgent need for reliable biomarkers of the efficacy and paradoxical reactions of biologics.