Duration
Swelling of the eye can last for varying lengths of time. Swelling that occurs after getting up usually disappears within a few hours. If the eyes are swollen due to an allergic reaction, the swelling disappears relatively quickly, the allergenic substance has disappeared relatively quickly or as soon as an anti-allergic treatment (e.g. eye drops) has been administered. If swelling persists for longer than one day or recurs without any apparent cause, the person affected should always consult a doctor.
Swelling only on the eyelid
The eyelid is a very sensitive structure consisting of tiny muscles and a thin layer of skin. Accordingly, the eyelid is very sensitive to irritation or infection. Often a swelling, which only affects the eyelid, is caused by an inflammation of the glands at the edge of the eyelid.
The sebaceous glands (also called meibomian glands) can become clogged and infected, the resulting clinical picture is called chalazion or hailstone. Likewise, a bacterially caused inflammation of the eyelid margin (blepharitis) leads to swelling and redness on the affected eyelid.