Effect of non-invasive intranasal neurostimulation on tear volume, dryness and ocular pain.

Purpose: To evaluate the effect of one TrueTear session on change in tear volume and symptoms of dryness and ocular pain.

Methods: Retrospective interventional case series of patients seen in a dry eye clinic. Seventy-five individuals underwent an ocular surface examination and one session of neurostimulation. Outcome measures included objective change in tear volume measured via phenol red test, and subjective change in sensations of dryness and ocular pain measured on a 0-10 Numerical Rating Scale.

Results: The mean age of the 75 individuals was 59±13 years, and the majority were male (73%). Intranasal neurostimulation increased tear volume (mean 13.40±8.00 mm, p<0.0005) and reduced intensities of dryness (mean -2.85±2.79, p<0.0005) and ocular pain (mean -1.48±2.41, p<0.0005 for both). However, these effects were independent of one another as change in symptom report did not correlate with change in tear volume (r=-0.13, p=0.25 for dryness; r=0.07, p=0.56 for pain). In a multivariable model, the strongest predictors for increased tear volume were lower baseline tear volume (standardised beta (β)=-0.50, p<0.0005) and absence of an autoimmune disease (β=-0.36, p=0.001) (R=0.30). The strongest predictors for reduced dryness and pain scores were lower baseline dryness and ocular pain scores. No complications related to neurostimulation were noted.

Conclusion: Intranasal neurostimulation increased tear volume and reduced intensities of dryness and ocular pain, independently of one another.