Musannaf Ibn Abi Shaybah

Hazrat Makhool said that when both eyelids of the eye would be removed, people would fix the full blood money (diyah), and they did this because after their removal, there is no protection left for the eye. And if only one is removed, then for the lower one they would fix one-third, and for the upper one two-thirds, because the upper one provides more protection compared to the lower one; it covers the eye and shields it from (external objects).