Dry eye, or keratoconjunctivitis sicca, is a pathologic condition which, today, needs to be more precisely defined. The moisture in the eye, which is essential for optical and physiological reasons, is maintained by three factors: a) the secretion of mucus by the conjunctiva, rendering uniform distribution of the aqueous phase of the lacrimal film on the corneal surface possible; b) the secretion of aqueous humor by the lacrimal and conjunctival glands; and c) the secretion of lipids from the skin and meibomian glands. Accordingly, an insufficiency of the lacrimal film may be due to insufficient secretion of lipids from the skin or meibomian glands, insufficiency of the aqueous phase of the lacrimal film (as is the case in Gougerot-Sjögren syndrome), or insufficiency of the mucus secretions (as in the case of pemphigoid syndrome). The complaints which lead patients to consult an ophthalmologist, as well as the objective findings on examination, are described here. The methods of examination by which lacrimal insufficiency can be confirmed are discussed: Schirmer's test (I and II), Jones' test, Norn's dilution test, break-up time, tests with dyes such as fluorescein, rose bengal, and lissamine green 1%. The conjunctival imprint gives indications without which no clear diagnosis can be made. The treatment of dry eye consists primarily of instillations of artificial tears. If this treatment fails the lacrimal puncta can be closed. Thirdly, pathogenic treatments can be used in certain cases. Fourthly, one can prescribe closed frames which create a wetting chamber. Finally, in particularly severe cases, surgery can be considered.(ABSTRACT TRUNCATED AT 250 WORDS)