[Functional dominance in the lacrimal canaliculi]

Past reports ignored the functional relationship between the upper and lower lacrimal canaliculi. The authors measured the lacrimal function in 50 normal eyes of 27 subjects and found that the drainage was more rapid in the lower lacrimal canaliculi of 25 eyes and in the upper canaliculi of 22 eyes, while the drainage time was equal in 3 eyes. The drainage in 25 eyes with both the upper and lower canaliculi open was more rapid than with any one canaliculus occluded. The authors suggested that the function of the lacrimal canaliculi might be classified into three types: the dominating, the dominated and the balanced. There was no statistical difference (P greater than 0.05) between the numbers of dominating upper or lower canaliculi in this series. The function of the upper and lower canaliculi operated synergically and complete drainage was not accomplished by any one canaliculus alone.