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.
It produces a toxin called Panton-Valentine leukocidin (PVL), which kills infection-fighting white blood cells and can cause recurrent skin infections, such as boils and abscesses, according to Britainâs National Health Service. An internal stye on eyelid is caused by an infection of the meibomian gland. These glands on the eyelids produce an oily liquid that makes up part of the tear film that covers your eye. Styes are sometimes a complication of another condition called blepharitis, which causes the rims of your eyelids to become inflamed. This can result in burning or sore eyes, crusty eyelashes and itchy eyelids. Most styes heal without treatment.