Electroretinograms as an indicator of disease activity in birdshot retinochoroidopathy

Purpose: To determine whether electroretinogram results can help predict the success in tapering of immunosuppressive medication in patients with birdshot retinochoroidopathy. Methods: Fifteen patients with birdshot retinochoroidopathy who had at least three serial electroretinograms (ERG) during the course of their disease were included in the study. Charts of patients seen at the Immunology and Uveitis Service at the Massachusetts Eye and Ear Infirmary, Boston, Massachusetts were retrospectively reviewed. Seven parameters of the ERGs were examined: dim scotopic amplitude, bright scotopic amplitude, bright scotopic implicit time, single-flash photopic amplitude, single-flash photopic implicit time, 30 Hz flicker amplitudes, and 30 Hz flicker implicit times. For each parameter the patients were divided into two groups, those with normal and those with abnormal responses at the time their immunosuppressive medication taper was initiated. The percentage of patients in each group who were able to successfully taper their immunosuppressive medication was calculated. A successful taper of medication was defined as no recurrence of disease signs or symptoms for at least 1 year after the medication was terminated. Results: Abnormalities in the bright scotopic response amplitudes and 30 Hz flicker implicit times were associated with recurrence of inflammation as immunosuppressive. therapy was tapered. Conclusion: ERG can serve as a useful adjunct in helping determine when to initiate tapering of immunosuppressive therapy in patients with birdshot retinochoroidopathy.