To establish accurate measurement of tear production in the diagnosis and monitoring of dry eye.Reexamination of the Schirmer test indicated that the rate of tear secretion decreases with advancing age. We measured the noninvasive tear film break-up time (NIBUT) in normal and dry eye patients with our original apparatus. The NIBUT showed a reasonable level of accuracy with a cut-off value of 5 seconds. The lactoferrin concentration in tear fluids subsequently was found to have a cut-off value of 1.1 mg/mL with an optimal level of accuracy.The present findings suggest that a combination of clinical tests is needed for the diagnosis of dry eye syndrome. The closed eye condition induces subclinical inflammation on the ocular surface. Fibronectin, a high-molecular weight glycoprotein, plays an important role in corneal wound healing, although its concentration in various types of tear has not been investigated. Fibronectin concentration in open eye tears (19 +/- 24 ng/mL) was significantly different (p = 0.004) from that in closed eye tears (4127 +/- 3222 ng/mL). During reflex tearing with nasal stimulus, the concentration increased significantly (p = 0.028) after 100 mL of reflex tears (220 +/- 126 ng/mL). Albumin concentration in the same samples showed a pattern similar to that for fibronectin. Administration of a topical vasoconstrictor eliminated the increase in fibronectin concentration during reflex tearing.These findings suggest that fibronectin in the tear fluid was derived from plasma and that the increase in concentration in closed eye and reflex tear fluid was caused by leakage from dilated conjunctival blood vessels.