[Relative discharge of tears by the upper and lower lacrimal ducts]

Forty eyes were studied in order to establish the relative function of the upper and lower lacrimal ducts. Following artificial occlusion first of the upper and then of the lower lacrimal ducts. Schirmer's No. 1 test was performed. The wetting of the test strips was used as an indirect measure of tear discharge. Higher quantities were discharged from the upper ducts of 17 eyes and from the lower ducts of 15. In 8 eyes the discharge from the upper and lower ducts was equal. The findings in this study thus disprove the commonly held belief that the upper lacrimal duct is plays a subordinate role in tear discharge.