This is secreted by the conjunctival goblet cells, the crypts of Henle and the glands of Manz.
(1) Functions:
Wetting of the cornea by converting the dorneal epithelium from a hydrophobic to a hydrophilic surface.
Lubrication
(2)Deficiency of this may be a feature of both hypo secretive and evaporative states.
The tear film is mechanically spread over the ocular surface through a neuronally controlled blinging mechanism and after a period of time is cleared through the nasolarcrimal drainage system .
The three factors required for effective resurfacing of the tear film are: (1) normal blink reflex,(2) congruity between the external ocular surface and eyelids and (3)normal corneal epithelium.
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