Mermaid Eye

Allrighty, so you've asked me to give you a critique for this one. Mind you, I'm not very much into photomanips the way it done here. However I do some retouching of my own captures, but never add, but I do remove stuff which are distraction.

I'll get straight to the point here. I think you should give more life to the eye. The way you can do this is by adding those tiny, tiny bloodveins (in lack of the correct enlgish word) to the completely white section of the eyes. You don't need to make them that visible to give you a leadingeffect.
You might also consider doing the purple part surrounding the iris a bit darker. This will create a swallowing effect to the eye.
Also I'd darken the gems on her eyelids some.

These are my opinions. As I said this is a bit out of my comfortzone, but I have an idea of how things should look to be more realistic.

You've done a really good job with your manips of the eyes linked from this image as well <img src="e.deviantart.net/emoticons/s/s…" width="15" height="15" alt="" title=" (Smile)"/>

Hope this was helpful <img src="e.deviantart.net/emoticons/s/s…" width="15" height="15" alt="" title=" (Smile)"/>