Sahih Muslim Book 7, Hadith Number 2742.

Chapter : The Muhrim is permitted to get the treatment for his eyes.

Nubaih b. Wabb reported: We went with Aban b. Uthman (in a state of ihram). When we were at Malal the eyes of Umar b. Ubaidullah became sore and, when we reached Rauba’ the pain grew intense. He (Nubaib b. Wahb) sent (one) to Aban b. Uthman to ask him (what to do). He sent him (the message) to apply aloes to them, for ‘Uthman (Allah be pleased with him) reported that the Messenger of Allah (may peace be upon him) applied aloes to the person whose eyes were sore and he was in the state of Ihram.