DISTURBANCES OF LACRIMAL FUNCTION
The two categories of lacrimal dysfunction are:
1- Inability of the drainage system to remove the tears produced.
This is caused either by:
a- Obstruction of the drainage system or overproduction of tears.
b- The clinical signs depend on the relative amounts of tears produced and drained away.
2- Failure to produce a normal precorneal tear film (or one of its components), usually resulting in secondary conjunctivitis and keratitis. Abnormalities are quantitative (insufficient aqueous component) or qualitative (abnormalities in components or function of the superficial lipid layer, or the inner mucoid layer).