the watery, slightly alkaline and saline secretion of the lacrimal glands that moistens the conjunctiva. See also lacrimal apparatus.
ophthalmic solutions formulated to replace tear secretion when it is reduced, as in keratoconjunctivitis sicca, by stabilizing the precorneal tear film. The most common preparations contain polyvinylpyrrolidone or methylcellulose.
tear1 film, precorneal tear1 film
the thin layer of lacrimal secretions covering the outer surface of the cornea; in conjunction with secretions from the meibomian glands and conjunctival goblet cells forms the preocular film. Deficiency of these secretions results in drying of the cornea and keratoconjunctivitis sicca.
tear1 film breakup time
an indicator of normal tear film function; premature breakup results in less protection of the cornea.
Schirmer tear1 test
see schirmer tear test.
tear1 staining syndrome
abnormal drainage with overflow of tears results in constant wetness and staining of facial hairs, usually in small breeds of dogs and brachycephalic cats.