Comparison between Upper and Lower Canalicular Tear Flow using Dacryoscintigraphy

ABSTRACT

We evaluated the relative tear flow in the upper and lower canaliculus using dacryoscintigraphy. 22 eyes were studied in 11 persons and the upper or lower punctums of both eyes were occluded with 0.3 or 0.4 mm diameter 1.75 mm long collagen plug and 13 of Technetium-99m sulphur colloid were placed in both eyes. Dacryoscintigraphy was performed in the upright position for 12 minutes. Using Pegasys. program, time-activity curve and T1/2 of radioisotope in the palpebral aperture were measured twice and the mean T1/2 was calculated. T1/2 values with the upper and lower canaliculus occluded were compared and analyzed. Of 22 eyes studied, 12 had more rapid tear transport in the upper canaliculus and 10 through the lower. The mean T1/2 of transport in the upper canaliculus was 703.2+/-789.2 seconds and 692.3+/-450.3 seconds in the lower. Tear drainage in the lower canaliculus was more rapid but this value was not found to be statistically significant (P=0.626 ). Therefore there was no significant difference between the upper and lower canalicular tear flow but individual variabilities. Considering these results, when punctum occlusion for the treatment of dry eye and reconstruction of canalicular laceration are performed we should equally weigh on both the upper and lower canaliculus.