Nevus of OTA is a hamartoma of dermal melanocytes, which often involves the gray-blue patches of the first and second branches of facial trigeminal nerve and ipsilateral sclera, most commonly in periorbital region, zygomatic region, nose, forehead and zygomatic bone. Half of the patients have blue-brown spots on their eyeballs, especially on a sclera, and the conjunctiva may also have pigmentation, which is a kind of birthmark. The etiology is unknown, and it may come from the embryonic period. Most patients exist after birth, and some patients begin to get sick several years after birth. Only a few patients get sick after trauma.