Introduction
A swollen conjunctiva, also called chemosis in medical terminology, is a glassy swelling of the conjunctiva. In most cases the whole conjunctiva is affected. Often, a blister-like lifting of the conjunctiva from the sclera is observed. Reasons for the swollen conjunctiva can be an inflammation of the conjunctiva (conjunctivitis), allergy, virus infection or mechanical irritation of the conjunctiva.
Causes
The swelling of the conjunctiva is primarily due to an increase in vascular permeability. In this process, fluid from the small blood vessels of the conjunctiva reaches the tissue, which then swells under the increasing volume. The swelling can occur within a very short time.
Reasons for the increased permeability of the vessels are usually allergies or viral infections. Inflammations and other irritations can also cause swelling of the conjunctiva. Also contact lens wearers may have a poor tolerance for the care product of the contact lenses, which can also lead to irritation and subsequently to a swollen conjunctiva.
More rarely, tumors in the eye socket can also block the outflow paths of the conjunctiva, which leads to a build-up of fluid and thus to swelling. Burns can also be the cause of chemosis. An allergy describes an immune reaction, i.e. a defence of the body against harmless substances.
These can be animal hair, pollen or food. Although these substances do not cause any damage, the body’s immune system takes action against them. A local immune reaction occurs in which certain substances turn against the structures of the allergen (e.g. pollen, animal hair).
In the place where the allergen causing the allergy is in contact with the body, the permeability of the blood vessels is increased and defense cells accumulate. In this case e.g. pollen enters the eye, which leads to an immune reaction and, among other things, to swelling of the conjunctiva. An allergic reaction usually occurs within 30 minutes on the mucous membranes and the eye. Apart from the conjunctiva, other organs such as the respiratory tract or the skin can of course be affected. An allergy can be treated mainly by avoiding the allergens and antiallergics.
