method for treating aqueous deficient dry eye by instilling a biologically compatible solute , such as sodium chloride , into the tear film continuously at a controlled rate that is sufficient to osmotically induce a continuous flow of water from the interstitial fluid to the tear film and thereby correct the aqueous deficiency . the method may be carried out by placing a therapeutic system , in the form of an ocular insert , into the cul - de - sac , the insert comprising the solute confined within a polymer matrix that releases the solute continuously at 3 to 20 micromoles of solute species per hour .