Background The objective of this study was to investigate the efficacy of topical 0.1% tacrolimus in treating refractory allergic conjunctivitis with proliferative lesions and/or corneal involvement.

Methods This prospective observational study included 1436 patients with refractory allergic conjunctivitis whose condition had responded poorly to conventional antiallergic drugs and/or topical steroids and/or topical cyclosporine. All patients received tacrolimus eye drops twice daily during the study period. Ten clinical signs and six clinical symptoms were rated on a four-grade scale. The primary endpoint was the change from baseline in total clinical signs and symptoms score at the last observation or following 6 months of treatment.

Results Total signs and symptoms score significantly decreased after 1 month of treatment (p<0.001). Giant papillae and corneal lesions were also reduced by tacrolimus eye drop use (p<0.001). The drug proved effective in patients whose condition did not respond well to topical cyclosporine therapy. About 50% of all patients using topical steroids were weaned. The most common adverse reaction was a transient burning sensation (3.20%).

Conclusions Tacrolimus eye drops are highly effective in treating refractory allergic conjunctivitis with proliferative lesions and/or corneal involvement, and may reduce or replace topical steroid use.

Trial registration number UMIN 000008640.