Symptoms. In most cases of eye melanomas, there are no initial signs that anything is wrong. It is only when the cancer of the melanin cells has multiplied significantly that a person will begin to suspect that they have a health problem. That being said, there are a few symptoms that a person can look out for. The first one is a sensation that there is something in the eyes that can’t be flushed out with water, like dust or debris. Next, is a change in the ability to see a wide area all at once, which is called the peripheral vision. The pupil will develop an irregular shape too. And, finally, a dark spot will develop on the iris that keeps growing in size.