The hair loss and redness above the cat's eyelids may be caused by a variety of reasons. This could be a sign of some kind of skin problem, here are some possible causes:

Parasite infection, such as scabies or lice.

Fungal or bacterial infection, causing skin inflammation.

Anaphylaxis, which may be allergic to food, environment or other factors.

Autoimmune diseases.

Injury or irritation, such as rubbing or scratching.