Blepharitis is the collective term for inflammation of the lid margin, which includes inflammation of the lid surface, eyelash follicles, and glands, and is one of the most common ocular diseases, usually subacute or chronic. Depending on the anatomic location, blepharitis can be divided into anterior blepharitis (mainly involving the anterior lid margin and eyelash follicles) and posterior blepharitis (mainly involving the lid glands). Depending on its pathogenesis, it can be divided into scaly blepharitis, ulcerative blepharitis, and canthal blepharitis. Common clinical manifestations: eye pain, eye itching, burning sensation, foreign body sensation, eye redness, dryness, photophobia, lacrimation, and increased secretion. Signs: lid margin congestion and edema, thickening, scar formation; lid margin crusting, ulceration, eyelash changes (loss of eyelashes, disorganization, follicular epithelial hyperplasia, cuff-like scales or scabs at the root of the eyelashes); obstruction or keratinization of the lid gland opening, lid gland atrophy or chalazion formation; tear film abnormalities. The diagnosis of blepharitis is not difficult, but treatment requires early, timely control of the symptoms and identification of the cause, which can be treated with the appropriate medication, as if the disease is prolonged and turns into chronic inflammation, it may lead to recurrent episodes and eventually cause eyelid scarring and other related eyelid disorders.