Choose any Ripped edged brush and Do several strokes inside the selected are with different colors.

Very fast!



Choose a filter, but before this further the selection by 3 - 5 pixels.



Apply Redial blur (ZOOM) to the selected area.



And here is the result of all this Fast made madness :).



Well, defiantly looks like onside of the eye. I tell you it was created in less than a minute.

I would like to color balance this a little bit. Hue saturation and Color balance tools.







Drag the layer to this very position beneath the black circle.







Create clipping mask.



Here we have.



I will warp my initial layer to make a form that is closer to human eye.



I'm also changing some layer styles settings of this very layer.







And we a re ready with this one. Our element is ready.

Now you probably know one of the fast ways to create a human eye.

Enjoy and I hope you found something useful for you. Cheers.