Abstract
Aim: To investigate differences in the clinical outcome of retrobulbar irradiation at 12, 16 and 20Gy.
Methods: A total of 113 patients (n= 44; 12Gy, n= 43; 16Gy, n=25; 20Gy) were examined prior to (t0) as well as 4-6 months after irradiation. Outcome was evaluated through proptosis, horizontal and vertical ocular motility, edema status and clinical activity score (CAS). Overall group and individual changes were evaluated. Success was defined as reduction of proptosis by more than 1.5mm, improvement of horizontal and vertical motility by >=5° or unchanged when normal at t0 and an CAS score of <=3.
Results: Prior to irradiation neither age, disease duration, gender, smoking behaviour, serum TRAb- concentrations nor CAS or NOSPECS stages varied significantly between all groups. Neither did outcome measures differ significantly. After irradiation CAS, edema status, vertical motility (except for 12 Gy) was improved significantly in all groups, while proptosis and horizontal motility did not. Inactivity was obtained in 70%, 69% and 70% of the patients respectively. Vertical motility improved by >=5° or remained unchanged when normal in 51%, 48% and 36% and horizontal motility in 72%, 88% and 97% of the patients respectively. Proptosis improved by more than 1.5mm in 53%, 43% and 42% of the patients respectively. There was a significantly higher amount of improvement in vertical motility at 16 and 20Gy than at 12Gy. No other outcome measure differed significantly between the groups.
Conclusion: Comparison of three different irradiation doses revealed no significant differences in the success rates concerning CAS and proptosis reduction and improvement of ocular motility. The only dose dependant difference was seen for the amount of improvement in vertical motility with a more pronounced effect for at higher doses.