Strobist info: Using a AF Micro 60mm I was really close I don't own a ring light so, I used a plastic plate with a hole to diffuse two sb600 placed in both sides of the lens. Distance is important in order to keep the highlights inside the pupil.
I'm figuring out how to light this type of scene with but any lightsource bigger or placed elsewhere produces ugly catchlights on the eye. The lens barrel is another problem when lighting being so close to the eye.