Blepharitis
Blepharitis is chronic inflammation of the eyelid margins: anterior disease affects the lash line, while posterior disease is usually meibomian gland dysfunction. It causes sore, gritty, crusted lids and evaporative dry-eye symptoms; long-term lid hygiene is the foundation, while pain, visual change or a very red eye needs urgent assessment for another ocular diagnosis.
Definition
Blepharitis is chronic inflammation of the eyelid margins. It may be anterior, affecting the lash-bearing margin, or posterior, most commonly reflecting meibomian gland dysfunction; the patterns frequently coexist and cause ocular-surface irritation and tear-film instability.
First principles
The site of inflammation defines the pattern
Anterior blepharitis affects the front edge of the lid around the lash bases. Posterior blepharitis most commonly reflects meibomian gland dysfunction (MGD), affecting the inner lid margin; both patterns can coexist. The meibomian glands produce the oily layer of the tear film, so posterior disease commonly produces evaporative dry-eye symptoms.
This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.

