This drawing of 'Golden Eye' by Daria Dzyuba is amazing! He has just used 4 colours (dark yellow, light brown, dark brown and black) and HB mechanical pencil. For the brightness of the eye he has used a rubber and white gouache.
This photograph/image of a humans eyes portrayed the exact feeling of 'Lost' I was looking for. It has proved to be useful in helping me to create a feeling in my subjects eyes as well as a reference to how light falls from above a subject.