Causes of blepharitis 

Blepharitis occurs when the edge of your eyelids become inflamed (they turn red and begin swelling). It is usually caused by an infection or a skin condition.

There are two main types of blepharitis:

  • anterior blepharitis  where the inflammation affects the skin around the base of your eyelashes
  • posterior blepharitis  where the inflammation affects your Meibomian glands (found on the inside edge of your eyelids)

Some people experience both types of blepharitis, as the causes are often linked.

Anterior blepharitis

Anterior blepharitis can be caused by either a bacterial infection or a skin condition called seborrhoeic dermatitis.

Staphylococcus bacteria are most commonly associated with blepharitis. These bacteria live harmlessly on the skin of many people but, for unknown reasons, they can cause the eyelids of some people to become inflamed.

Seborrhoeic dermatitis is a skin condition that causes skin to become oily or flaky, and it can sometimes irritate the eyelids. Seborrhoeic dermatitis often causes both anterior and posterior blepharitis at the same time.

Anterior blepharitis has sometimes been linked to demodex, which are microscopic mites that live on eyelashes. These mites are usually harmless, but may cause blepharitis in some people  possibly due to the eyelids becoming damaged or because of a sensitivity reaction. Some types of demodex mite have also been linked to cases of posterior blepharitis.

Posterior blepharitis

Posterior blepharitis occurs due to a problem with the Meibomian glands, which are found on the inside edge of your eyelids.

The Meibomian glands are responsible for producing an oily substance that makes up part of your tears. A problem in these glands can lead to excess production of this oily substance or a blockage in the glands, which can cause the eyelids to become irritated and inflamed.

Excessive production of the oily tear substance is often linked to seborrhoeic dermatitis (see above), while blockages in the Meibomian glands are often due to a skin condition called rosacea.

Rosacea is a common, long-term skin condition that mainly affects the face. The first symptoms are usually episodes of flushing (when the skin turns red), but eye problems such as blepharitis develop in around half the people with the condition, as it progresses.

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Page last reviewed: 22/04/2014

Next review due: 22/04/2016