Here are two different versions I edited and the feedback I received:
1) I experimented with the vivid colour tool under the burn tool options and found that it accentuates the veins in the eyes.
- The colours do not stand out enough to make it look scary
- The skin needs to look smoother and the tone more even
2) I combined the vivid colour tool with a burn tool to make the eyes stand out more.
- Not realistic, but it looks frightening