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.
1 Swelling of 1 eye is often due to an insect bite. Mosquito bites are a common cause. It can also be from an irritant e.g. food transferred to the eye by the hands.  Suspect mosquito bites if there are bites on other parts of the body. Insect bites of the upper face can cause the eyelid to swell. This can last for a few days. With insect bites, the swelling can be pink as well as large.