It goes against your copyright if someone uses your work without written permission,
I would contact that person by every means possible to get them to remove the work or if you want get credited for your part, if they don't not only would I report them to the site but I have had friends speak to their copyright people to take it further.

If they don't ask your permission or even cite you, then it's art theft!

You're so right to report them if they are using your eyes as their own.

If their using your actual eye manips, then that's plagurism. You have every right to report it xx

Absolutely not.

Report it. Let them know that it isn't okay so that they don't keep on going in the same style and eventually find someone who doesn't hesitate to sue.

No. It means you're doing the right thing.