Topical therapy for dry eyes.

'Artificial tear' solutions, perhaps more accurately termed 'ocular wetting' solutions, have been the mainstay of topical therapy for keratoconjunctivitis sicca (KCS). These solutions have been designed with water-soluble polymers in an attempt to increase their ocular retention time or ability to wet the ocular surface. Treatment with ocular wetting solutions has been non-specific in that there is no evidence that dry spot formation is essential to the induction of surface disease in KCS patients, nor is there evidence that water-soluble polymers are beneficial to epithelium. In KCS, tear film osmolarity is abnormally elevated by potentially complex mechanisms that result from decreased aqueous tear secretion. The abnormal osmolarities observed in KCS produce the major ocular surface abnormalities seen in this disease. In a double-masked trial, a 150 mOsm/L solution, selected from a range of hypotonic solutions for its ability to lower elevated tear film osmolarity optimally in KCS, has been shown to be superior to an isotonic 300 mOsm/L solution in providing symptom relief for KCS patients.