Immunosuppressive therapy is well established in the treatment of thyroid eye disease (TED). The best response has been observed in those with active (wet phase) disease of short duration. A prospective study was designed to observe the effects of orbital radiotherapy and oral immunosuppression on patients with TED, and to assess whether any pre-treatment parameters were predictive of the outcome. Significant improvements in uniocular fields of fixation (UFOF) and in the Mourits' disease activity scale were seen after treatment. The degree of improvement in UFOF was positively correlated with the level of initial disease activity. The use and technique of UFOF in assessing disease phase and activity are discussed.