The first two wave types, P and S , are called body waves because they travel or propagate through the body of Earth. The latter two are called surface waves they the travel along Earth's surface and their amplitude decreases with depth into Earth.
The causes are many and can have bacterial infection, seborrheic dermatitis of the face or even a scalp, rosacea, allergies, and in very rare cases, the lice. If the itchy eyelids is brought about by seborrheic dermatitis then you may develop dry, flakey patches of skin on the eyelid.
Eyelid swelling has many causes (see Table: Some Causes and Features of Eyelid Swelling). It usually results from an eyelid disorder but may result from disorders in and around the eye socket (orbit) or from disorders elsewhere in the body that cause widespread swelling.