Inspired by the “Swamp Thing” thread, I have been playing with methods of making eyeballs in ZB based on the many tutorials on this forum. I hope to bulid a complete list here of all of them so that they can be more easily found.
Searching for “EYE” yields no fruit so hopefully “EYEBALL” will be enough.
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Added some time lapse images.
its better if you can upload a zscript or soem kind of tutorial or even the finshed texture - that would really help all to tryout your version as well 
This shows more of what I am doing. Using 2nd layer to get cornea (lens) effect. I used color intensity as alpha to texture the iris. (see time lapse in previous post). texture is includes here. I will try to make more of a tutorial as time allows, to share what I am doing…
Here’s a couple. They don’t cover the 2nd layer thing though.
Moochie’s Newb challenge is good on texturing eyes in z.
http://www.zbrushcentral.com/zbc/showthread.php?t=28664
Moochie’s Newb challenge on lids that fit!
http://www.zbrushcentral.com/zbc/showthread.php?t=29548
Don’t want to be picky, but your iris is too small for your eyeball. It should be just less than 1 third of the overall hight/width.
zoe instead of creating a tutorial save the zscript after you finish doing work on a document in zbrush - just go to zscript and press end button after you finshed working -this will export a txt file which when run in zbrush on any computer will create excatly the way you created it in zbrush. But you will have to provide any additional 3d models you used or materials which are not in the default pallete.
Thats the interactive learning experince 
Rememeber it next time.
OK, my first zscript. Run Brown eye1 save the tool and then run Brown eye12.