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.
These can be caused by irritation of the surface of the eye (cornea) or the membranes lining the eyelids (conjunctiva). Sometimes, the reason your eyelid is twitching cannot be found. This form of eyelid twitching lasts much longer and is often very uncomfortable. It can also cause your eyelids to close completely. Repeated uncontrollable twitching or spasms of your eyelid (most often the upper lid)