I'm a newbie and I wanted to check out how I can make my own eyes for the creatures I may create and how I can do it. After some tries it's working now. Using a light-brown blotchy leather texture as background. Use it for your models or what ever you want to do with it. Please let me know if they don't fit and give me a hint how I can do it better. Have fun.
CC0 - Creative Commons Zero