The tear film is actually very complex containing several proteins, but to keep things simple, it consists of three layers; an oily (lipid) layer, a liquid (aqueous) layer and a mucous (mucin) layer. The mucous layer effectively acts like a glue to help the tear film stick to the cornea. The liquid layer helps the cornea breathe, is antibacterial, and helps to wash away dirt and debris. The oily layer helps to prevent the liquid layer from evaporating, helps to keep the liquid layer in place-otherwise the tear film would just get pushed out of your eye onto your skin, especially when you blink. The lipid layer also protects the skin around the eyelids.
A defect in any of these layers would mean a destabilisation in the whole of your tear film, and this is when dry eye can occur giving you the classic symptoms.
Blepharitis largely occurs when there is a deficiency in the lipid layer of the tear film, which is what we aim to target and treat at Eyedro.