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

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

Double-blind, randomized controlled pilot study.

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

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.

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.

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.