The authors look at the role of the FDDT in the evaluation of adults with primary acquired nasolacrimal duct obstruction (PANDO) and its correlation with the age and severity of epiphora. They report the results of a prospective cross-sectional comparative study looking at FDDT at two, five and 10 minutes in 58 eyes of 58 patients with PANDO and, as a control, they also looked at the same number of cases without epiphora. Patients with functional, incomplete obstruction or upper lacrimal system obstruction were excluded. They found that the two minute FDDT showed a sensitivity of 82.8%, specificity of 91.4%, positive predictive value of 90.6%, and negative predictive value of 84.1%. The five minute FDDT showed a lower sensitivity and negative predictive value but an increased specificity and positive predictive value. They found no correlation between FDDT and severity of epiphora or age. The results support the continued use of the FDDT as a simple, reliable and specific test in the evaluation of PANDO in adults.