Definition: Inflammation of the eyelids, where the lid becomes red, itchy, scaly, with dandruff and debris in the eyelashes
Anatomy: The lids are divided in two portions: external lids, covered with skin, and internal lids, covered with a transparent tissue called the conjunctiva
There are different subtypes of blepharitis, they are very common.
External Blepharitis or Anterior blepharitis occurs at the outside front edge of the eyelid where the eyelashes attach. Posterior blepharitis affects the inner edge of the eyelid that touches the eyeball.
Internal Blepharitis affects in the inner part of the lid that touches the eye
Meibomian Gland Dysfunction affects small glands located in the lid margin responsible to secrete lipids into the tear film. When they become chronically inflamed, people will often develop dry eyes
In special circumstances, the eyelid glands become suddenly infected and inflamed, it is commonly known as a stye.
Technically eye doctors call it a hordeloum that can be external or internal depending on the location of the gland that is inflamed. They always present as sudden, red, swollen, painful to the touch area of the eyelid. Traditional treatment methods include the use of warm compresses to help drain the solid material. Topical eyedrops and ophthalmic ointment are not very useful, specially for internal styes. When the stye is serious enough, your eye doctor may decide to use oral antibiotics to help combat the infection. Only oral antibiotics can penetrate deep enough inside the lid to be effective on the infection. Typical antibiotics optometrists use for styes include antibiotics from the tetracycline family (Doxycycline), which have both antibiotic and anti-inflammatory properties; penicillins such as amoxicilin or macrolides such as azithromycin.
In some patients, the infection tends to spread from a localized area in the eyelid to the whole eyelid. If the infection spreads but stays superficial it is called a preseptal cellulitis. If the infection is deep and generalized, it is called an orbital cellulitis. Both of those clinical entities are treated with oral antibiotics but the latter is a medical emergency that must be addressed as it can be life threatening if the infection spreads behind the eye.