[Intensity-modulated radiotherapy of head and neck cancers: Dose effects on the ocular, orbital and eyelid structures].

Radiation-induced damage of ocular, orbital and eyelid structures are mainly reported for the optic nerve, retina, lens and lacrimal gland. Dose-volume relationships are, however, inaccurate due to the small volume of most of the organs at risk involved and limited ability of irradiation techniques to spare these structures in the pre-IMRT (intensity-modulated radiation therapy) era. The ability of newest radiation techniques including IMRT and proton therapy to generate steep dose gradients may yield more accurate models in the future. Some toxicities are severe and irreversible, leading to vision loss, as in the case of radiation-induced optic neuropathy for which curative treatments are suboptimal. Other toxicities can lead to reversible vision loss but can be surgically corrected, as is the case for radiation-induced cataract. In this paper, we will review the dose effects for the ocular; orbital and eyelid structures.