The outer surface of the eye is a specular glass material, so if any lights catch the eye they will reflect a highlight. With her head at that angle and the sun where it is there just aren't any highlights. If I boost the reflectivity slightly they may pick up the blue of the sky or something, so I'll try that and see if it looks right.

I can see her eyes anyway, but maybe they need a boost.

I'll be working on this again tonight and tomorrow, so if I don't post later tonight then expect something tomorrow evening, UK time.