Realistic eye tutorial

This is a quick demonstration of how one can draw somewhat realistic eyes step by step. 

1. Start with creating a rough outline, almost cartoon like, just to get a basic idea of the shape of the eye.
   
2. Add some detail, but keep the design simple still, in case you notice that you have gotten the positioning wrong. You do not want to use the eraser more than neccessary.
   
3. Once you have positioned the details, you might want to erase (or at least lighten) the lines you used in the initial sketch. When drawing realistically, you want to avoid sharp lines, and place more focus on shading.
   
4. Continue adding details and building volume with shading.