Abstract:Objective To study the effect on normal ocular tissues after intensity-modulated radiotherapy (IMRT) in the patients with nasopharyngeal carcinoma. Methods Nineteen nasopharyngeal carcinoma patients confirmed by pathology were enrolled (38 eyes). All Patients underwent visual acuity, slit lamp, fundus, visual evoked potential (VEP) and electroretinograms (ERG) examination before IMRT, at the end of IMRT, 6 months and 12 months after IMRT. Results ① There was no statistically difference in uncorrected and corrected visual acuity at the various examination time points before and after radiotherapy (P＞0.05). ② Theaverage latency of VEP P₁₀₀before IMRT,at the end of IMRT, at 6 months after IMRT and 12 months after IMRT was (99.684±2.484) μV , (99.947±2.277) μV, (104.000±3.952) μV and (101.316±2.462) μV respectively. The average latency of VEP P₁₀₀was significantly prolonged at 6 months after IMRT compared with the time points of before IMRT, the end of IMRT and 12 months after IMRT (P＜0.05). ③ The average latency of ERG b wave before IMRT , at the end of IMRT, at 6 months after IMRT and 12 months after IMRT was (44.974±3.774) ms, (44.816±3.368) ms, (43.184±2.837) ms and (44.000±3.154) ms respectively。The average amplitude of ERG b wave before IMRT, at the end of IMRT, at 6 months after IMRT and 12 months after IMRT was (421.237±27.353) μV, (414.763±26.188) μV, (419.026±24.876) μV, and (419.974±25.894) μV respectively. No statistically difference was found in average latency and amplitude of ERG b wave at the various examination time points before and after radiotherapy (P＞0.05). ④ The average amplitude of Op2 wave before IMRT, at the end of IMRT, at 6 months after IMRT and 12 months after IMRT was (63.184±6.028) μV, (48.605±6.872) μV, (50.421±6.769) μV and (53.026±6.074) μV respectively. At the various time points after IMRT, the average amplitude of Op2 wave was significantly lower than before IMRT (P＜0.05).Conclusion IMRT can significantly reduce the incidence of ocular complications. There is a good clinical application value of ERG and VEP for evaluating retina and optical nerve functional changes induced by IMRT. 

Key words:Radiotherapy, intensity-modulated,Nasopharyngeal neoplasms,Ocular complications