The role of azathioprine in the management of retinal vasculitis

Purpose Azathioprine is commonly used as a second-line immunosuppressive agent in the management of patients with retinal vasculitis. The aim of this study was to determine the efficacy of azathioprine by evaluating its effect on relapse rate, clinical outcome and maintenance steroid dose. Methods A retrospective analysis was performed of 34 patients presenting over 15 years to the Medical Eye Unit at St Thomas' Hospital. Relapse rate, steroid dosage, inflammatory score and visual acuity were assessed before and during treatment with azathioprine. Results Thirty-four patients (23 male) aged 17-70 years (median 41.4, median 38) were enrolled. Fifteen had idiopathic retinal vasculitis, 12 had Behcet's disease, 2 sarcoidosis, 2 sympathetic ophthalmia, 1 birdshot retinochoriodopathy, 1 Still's disease and 1 Harada's disease. The principal indications for azathioprine treatment were uncontrolled disease despite appropriate steroid therapy in 28 patients (82%) or to permit a decrease in steroid dosage in 6 patients (18%). Frequency of relapse was assessed in 10 patients whose pre-treatment and treatment periods with azathioprine were of 1 year or greater. All were found to have a decreased replapse rate. In 60%, reduction of steroid dosage was achieved. Ocular inflammatory score decreased in 56% of eyes and visual acuity was improved or maintained in 64%. In 8 patients treatment had to be stopped due to side effects. Conclusion Within the limitations of a retrospective study, we found azathioprine when used in combination with systemic steroids to be most effective at reducing the relapse rate of retinal vasculitis, but only partially effective in allowing a reduction in steroid dosage.