Objective: The authors describe a new and simple procedure, the Micro-Reflux Test (MRT), to screen for primary acquired nasolacrimal duct obstruction (PANDO). This study sought to determine the reliability of this new test in the diagnosis of complete nasolacrimal duct obstruction.
Design: A nonrandomized, prospective, self-controlled, comparative case series.
Participants: Two hundred eyes of 100 patients with documented unilateral complete PANDO were examined.
Intervention: The MRT was performed by a masked examiner on both eyes of each patient. Two drops of 0.25% sodium fluorescein dye were instilled in the inferior cul-de-sac and the patient made to blink five times to activate the lacrimal pump mechanism. Excess fluorescein dye was blotted away using tissue paper. The patient was positioned at the slit lamp, and observation of the inferior punctum with the cobalt blue filter was done using 5x magnification. The tissue overlying the lacrimal sac was massaged in a counterclockwise direction with moderate pressure using the index finger. The test was considered positive if there was continued observed reflux of fluorescein-stained tears from the inferior punctum after the initial counterclockwise massage to empty the inferior canaliculus. The validity of the MRT was measured by sensitivity and specificity as well as positive- and negative-predictive values.
Main outcome measure: The MRT was considered positive if there was continued reflux of fluorescein-stained tears from the inferior punctum after the initial digital massage to empty the dye from the inferior canaliculus.
Results: The MRT used for the evaluation of complete PANDO has a sensitivity of 97% and a specificity of 95%. It has a positive-predictive value of 95% and a negative-predictive value of 97%.
Conclusion: The MRT is a reliable screening test for presence of complete nasolacrimal duct obstruction.