Duplicate this sphere using Shift + Scale. This way you'll have two spheres in the same place. Select the new, larger sphere and then select the edges shown in Fig.10 and chamfer them (Fig.11).



Apply a MeshSmooth modifier and play with the geometry. You want to make a bulge in the front of it, like the one shown in Fig.12.


Now select the inner sphere and use soft selection mode to reshape the geometry and flatten out the front of it. That area will be our iris and you should now have something like this (Fig.13).




The final eyeball geometry should be like this one (Fig.14).


Notice that the scale difference between the two spheres is very slight. For placement of the eyeball in the head mesh, I recommend using a sculpting software while the sculpting of your head mesh is being completed. After you've placed the eyeball correctly, import both the head and eyeball meshes back into 3ds Max (Fig.15).