As shown in Table 1, 25 of 1845 patients developed RON, yielding an incidence of 1.36% (95%CI: 0.94 – 1.89%). This figure is not significantly lower than that reported by Eastman et al., who calculated an incidence of 2.2% (95%CI: 1.53 – 3.17%) (P = 0.10)25. The incidence reported by Eastman et al. is likely to be overestimated, because they included single case reports of RON in their review25. Although the incidence of RON is low, it is considered a serious complication of radiation therapy. It is therefore of interest to identify the severity of visual loss and the radiation treatment characteristics associated with its occurrence.

Table 1 (click to view)