Clinical study on the effectiveness of tear drainage with a single canalicular system under environmental stress.

Sixteen asymptomatic volunteers had their right lower puncta occluded with a Freeman silicone plug. They then went about their normal daily activities for approximately 1 week under the stress of a cold Chicago winter. Of the 16 eyes that were plugged, 4 had epiphora. The episodes were of short duration and did not have any effect on the subjects' daily activities. When comparing the incidence of epiphora between the plugged eyes and the control eyes, there was no statistically significant difference (p = 0.082). Also, when comparing the modified Jones I test and Schirmer tests, with and without anesthesia, there was no significant difference in the values between the plugged and the control eyes (p > 0.05). The only difference noted was in the dye disappearance test (p < 0.05). These results support the hypothesis that in selected patients, even under stressful environmental conditions, a single healthy canaliculus may provide sufficient tear drainage from a normal eye to prevent bothersome subjective symptoms.