Novel taste test for nasolacrimal duct obstruction using denatonium benzoate: a randomized controlled pilot study.

Objective: To evaluate a novel, simple, noninvasive method (known as the "bitter taste test") of establishing nasolacrimal duct patency in healthy asymptomatic eyes.

Design: Double-blind, randomized controlled pilot study.

Participants: Healthy asymptomatic medical students, residents, and allied health staff at our institution.

Methods: Participants, aged 18-35 years (n = 28) with assumed normal lacrimal function, were randomized to the interventional group (100 parts per million denatonium benzoate in sterile water, n = 14) or to the control group (sterile water only, n = 14). All participants were pretreated with topical tetracaine in their right conjunctival cul-de sac, followed by 3 drops of the experimental solution spaced 1 minute apart. The primary outcome was whether participants reported a strong, persistent bitter taste. The secondary outcome was the time-to-taste. All participants received lacrimal irrigation. The Fisher's exact test was done using GraphPad online software.

Results: All participants in the interventional group reported the presence of the bitter solution. None of the participants in the control group reported bitterness (p < 0.001, Fisher's exact test). Time-to-taste was within 15 minutes for 71% of the intervention group (n = 10); within 30 minutes for 79% (n = 11); and within 2 hours for 100% (n = 14). The bitterness typically persisted for 1-2 hours. All participants had normal lacrimal systems to irrigation. No adverse events were reported.

Conclusions: The bitter taste test demonstrates a promising ability to assess nasolacrimal duct patency under physiologic conditions in healthy participants. Further research is needed to validate this method in a clinical sample of patients with nasolacrimal duct obstruction.