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Effect of non-invasive intranasal neurostimulation on tear volume, dryness and ocular pain
  1. Monika Farhangi1,
  2. Anny Mansim Cheng1,
  3. Brandon Baksh2,
  4. Constantine D Sarantopoulos2,3,
  5. Elizabeth R Felix1,4,
  6. Roy C Levitt2,3,
  7. Anat Galor1,2
  1. 1Ophthalmology, Miami VA Medical Center, Miami, Florida, USA
  2. 2Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA
  3. 3Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami, Miami, Florida, USA
  4. 4Physical Medicine and Rehabilitation, University of Miami, Miami, Florida, USA
  1. Correspondence to Dr Anat Galor, Ophthalmology, Miami VA medical center, Miami, FL 33125, USA; agalor{at}


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) (R2=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.

  • ocular surface
  • diagnostic tests/investigation

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  • Contributors All authors substantially contributed to this manuscript. Data collection: MF and AG. Data analysis: MF, AMC, AG and ERF. Drafting manuscript: MF, AC, BB and AG. Critical revision of manuscript: MF, AMC, BB, CDS, ERF, RCL and AG.

  • Funding This study was supported by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Clinical Sciences, Research EPID-006-15S, NIH Center Core grants P30EY014801 and R01EY026174 (AG), an unrestricted grant from Research to Prevent Blindness. Allergan provided the TrueTear equipment for the study but was not involved in the design, conduct or analysis of study results.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.