Blepharitis is an inflammation of the eyelids and sebaceous glands of the margin of the eyelid. There are two main types: blepharitis squamosa and blepharitis ulcerosa. The squamosa type is characterized by redness (due to increased blood in the area) and the presence of white and gray scales. Usually, this condition is associated with seborrhea, which causes the formation of yellowish crusts around the lashes. Although the lashes may fall out, they are soon replaced. In the ulcerosa form there are also yellowish crusts, but when these are removed small ulcers are seen. Also, in blepharitis ulcerosa the lashes are lost permanently and the eyelid margin becomes thickened and distorted.
Blepharitis squamosa is usually treated with ointments of ammoniated mercury and selenium sulfide. The ulcerosa form responds to zinc oxide and antibiotic ointments.