Owls have 3 "eye-lids" for each eye. The top eye-lid and the bottom eye-lid which the owl uses when it sleeps. The nictating membrane is often referred to as the third eye-lid and is used to protect the owl's eye when it is hunting or flying. The membrane moves from the part closest to the bill and moves outwards. A healthy nictating membrane is normally transparent and relatively clear. Looks like something happened to this owl's right nictating membrane.