36 EWAP SEPTEMBER 2023 CORNEA relatively common after the age of 30. For example, 30% of people over age 30 have posterior blepharitis, and 50% of people age 50 have posterior blepharitis. “The way to distinguish them is anterior blepharitis has edema and redness of the lash margin and will form anterior abscesses at the lash margin,” Dr. Perry said. Posterior blepharitis will have pouting of the meibomian gland orifices and often has inspissation of dried secretions and will sometimes form caps of meibum over the gland openings. If left untreated, this will usually cause chalazia or abscesses of the meibomian glands. Dr. Perry said one of the reasons that blepharitis is tricky to diagnose is because there are five main factors: a microbiologic factor, dermatologic factor, allergic factor, nutritional factor, and meibum quality factor. Dr. de Luise said that anterior blepharitis due to staphylococcal organisms and posterior blepharitis due to meibomian gland dysfunction are among the most common forms. Another system is to describe the eyelid findings as ulcerative or non-ulcerative. Ulcerative blepharitis tends to be infectious in etiology, and non-ulcerative blepharitis is more likely inflammatory. Dr. de Luise offered a useful mnemonic device for the presentations and causations of blepharitis by remembering the letters ABCD. “A” is for anterior and allergic. This group includes allergic eczematoid blepharodermatitis, contact dermatitis, and atopic dermatitis. Allergic anterior blepharitis usually manifests as an eczematoid blepharodermatitis. Symptoms of anterior blepharitis include irritation, itching, and redness and scaling of the eyelid skin. “B” is for bacteria and viruses. These are the infectious causes, which include bacteria such as staphylococci and blepharitis due to viruses such as Herpes simplex, Herpes zoster, or Molluscum contagiosum. “C” is for cancer, chemical, clogging, and complex. This group includes papilloma, sebaceous cell carcinoma, melanoma, and basal cell carcinoma. Chemical refers to burns or thermal blepharitis. Clogging refers to the blockage of the meibomian glands in meibomian gland dysfunction. Complex refers to hybrid forms of blepharitis, which manifest both in the anterior and posterior lid. “D” is for Demodex and dermatologic. These etiologies include Demodex folliculorum (anterior blepharitis), Demodex brevis (posterior blepharitis), oculocutaneous rosacea, psoriasis, Stevens - Johnson syndrome, and cicatricial pemphigoid. In 2011, the International Workshop on Meibomian Gland Dysfunction stratified blepharitis into anterior and posterior types. It defined anterior blepharitis as inflammation of the lid margin anterior to the gray line and centered around the eyelashes. The gray line represents the location of the marginal region of the orbicularis muscle seen through the lid skin. The line divides the eyelid into an anterior lamella (eyelid skin and muscle) and posterior lamella (tarsus and conjunctiva). Anterior blepharitis may be accompanied by squamous debris or collarettes around the base of the lashes and vascular change. 3 The International Workshop defined posterior blepharitis as inflammatory conditions of the posterior lid margin, including meibomian gland dysfunction. The posterior lid margin contains the marginal mucosa, the mucocutaneous junction, the meibomian gland orifices and the terminal ductules, and the neighboring keratinized skin. Posterior blepharitis is a term used to describe inflammatory conditions of the posterior lid margin, of which meibomian gland dysfunction is only one cause, Dr. de Luise said. Other causes include infectious or allergic conjunctivitis and systemic conditions, such as oculocutaneous rosacea. 3 Presentation According to Dr. de Luise, in order to properly diagnosis blepharitis, it is essential to describe what one sees on Foamy tear film. Source: Henry Perry, MD
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