It is forbidden to derive benefit from the light of the Hanukah candles. Nevertheless, Hacham Ovadia Yosef cites several Halachic authorities (Rav Yaakov Kastro, Peneh Aryeh, and Rav Haim Palachi) who maintain that one may use the light of the Hanukah candles to avoid tripping or knocking into furniture. This kind of use does not qualify as "Hana’a" ("benefit"), as one uses the light only to avoid harm, and not for a positive purpose.
Accordingly, the Yalkut Yosef (p. 127; listen to audio recording for precise citation) rules that if there is a power failure while the Hanukah candles burn in the home, one is not required to close his eyes to ensure he does not benefit from the light. He may use the light of the candles to watch where he goes and ensure he does not get hurt, as this does not fall under the category of forbidden "Hana’a."
