Quantitative Lacrimal Scintigraphy in the Assessment of Epiphora
The transit of Tc-99m pertechnetate through 122 lacrimal drainage systems was quantified. Systems were categorized as having presac, preduct, intraduct, or no delay. Scintigraphy indicated an obstruction in 81.3% of eyes with epiphora. Of the 18 eyes in whom only scintigraphy revealed an obstruction, all 3 who underwent surgery experienced symptom relief. In patients presenting with unilateral epiphora the mean canthus half-time (12.9 vs. 7.2 minutes), time-to-peak activity at the sac (11.6 vs. 3.1 minute), and sac half-time (19.0 vs. 10.3 minutes) were significantly prolonged in the symptomatic eye. Similarly, the sac-to-canthus (0.32 vs. 0.72), duct-to-canthus (0.32 vs. 0.99), and duct-to-sac ratios (0.48 vs. 0.79) of peak activity were all significantly reduced in the symptomatic eye. When compared with "no delay," "presac," "preduct," and "intraduct" delay were significantly associated with attenuated clearance times or reduced ratios of peak activity corresponding to the level of obstruction. We conclude that there is a significant association between symptomatic epiphora and quantitative variables at the canthus and sac in lacrimal scintigraphy. Quantitative variables help locate the level of an obstruction.