By Sharon Kleyne, Research Director, Bio-Logic Aqua Research
Inflammation plays a central role in dry eye. One type of inflammation strongly associated with dry eye is Blepharitis, or eyelid inflammation. The majority of blepharitis patients also have dry eye symptoms. Blepharitis has many causes, but the lipid secreting meibomian glands, located within the eyelid, are almost always involved. Lipid production is critical to a properly hydrated eye because lipids trap and seal tear film moisture, preventing evaporation.
Three types of blepharitis
(1) Obstructive. This condition is marked by hardening (hyperkeratinization) of the eyelid margin and the meibomian gland ducts within the eyelid. The flow of lipids produced by the meibomian glands are not only obstructed but the lipids are thicker. Individuals with obstructive blepharitis exhibit high tear film evaporation, low tear flow and other dry eye symptoms. Eyelid examination could reveal missing glands that had previously been obstructed and were subsequently absorbed.
(2) Seborrheic. Individuals with seborrheic dermatitis (patches of red, inflamed skin caused by overproduction in the skin’s sebaceous or oil glands), often exhibit seborrheic blepharitis as well, marked by increased (rather than decreased) lipid production from the meibomian glands. Eyelid examination reveals normal morphology of the meibomian glands. However, patients with seborrheic blepharitis have dry eye more frequently than the normal population.
(3) Bacterial. Bacterial overgrowth on the eyelid margin also creates inflammation and contributes to eyelid hardening, causing meibomian gland obstruction. All eyelids have bacterial flora. Genetic mechanisms are also a factor since the level of free cholesterol partly determines the nature and extent of bacterial overgrowth.
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