Human tears: glucose instabilities.

Using a photometric method, a comparative analysis based on 717 human tear samples was made between systematically collected non-reflex, open eye tears and tears associated with prolonged eye closure (sleep), as well as for certain reflex provoking conditions (mild mechanical irritation, irritating vapours and osmotic imbalance). Although the closed eye tear glucose mean for the 8 young adults studied was found to be less than their open eye mean (5.01 versus 7.50 mg%), those two values were not found to be significantly different. However, statistical comparisons made between non-reflex open eye tears and the mechanical, irritating vapour and osmotic responses were found to be different at the P less than 0.05 level of significance, a higher mean concentration being found for the mechanical and osmotic conditions, and a lower mean concentration for the vapour induced condition.