Anterior Blepharitis –This condition affects the front part of the eyelid close to the roots of the eyelashes. It is commonly caused by bacteria that lives on your skin as they produce an irritating toxin that causes inflammation.
The lid margin often looks ‘crusty’ and when seen under a microscope, the appearance can be similar to dandruff. Anterior Blepharitis can cause the eyelids to become red, itchy and sometimes slightly swollen too.
Posterior Blepharitis –This is also often referred to as Obstructive Meibomian Gland Disease. The meibomian glands are located within the eyelid, and the pores of the glands open onto the rim of the eyelids behind the roots of the eyelashes. The glands normally produce a special oily substance for tears.
The meibomian glands can inflame and subsequently become blocked, causing a reduction of the amount of the oily substance that is produced. This can not only cause eyelid margin irritation, but can also cause the surface of the eye to become dry and irritated.