Well, it looks pretty darn good for a first eye, I must admit. But I do have some suggestions to help improve it and make it look even more realistic, assuming that's what you're going for :3
http://www.flickr.com/photos/weirdcolor/3326042456/I'm not sure if you used a reference or not, but as you can see in the photo above, it looks kind of similar to your eye that you drew. I would suggest moving the pupil to the center of the iris, as that's where is should always be, regardless of where the pupil is looking. I would also darken the perimiter of the pupil and be more eleborate with the inside of the pupil as well, though I guess it depends on the eye for the amout of intricacy due to it. Also, you might consider lengthening the eyelashes on top a bit, because those are generally longer than the ones on the bottom. Other than that, I think you're good! Love all of your artwork, btw <3
Hope I helped a little. Keep up the good work!