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Kari Basso Green, Manasi Kamat, Manfred Franke, Mark Holdbrook, Michelle Senchyna; Tear Total Lipid Concentration in Patients with Dry Eye Following Intranasal Neurostimulation. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2693.
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© ARVO (1962-2015); The Authors (2016-present)
The nasolacrimal reflex is a well-established pathway that plays a critical role in both bolus and basal tear production. The Intranasal Tear Neurostimulator (ITN) delivers a small electrical current to sensory neurons of the nasal cavity that stimulate the nasolacrimal reflex and induce tear production. The chemical composition of tears is essential for their optimized function. Numerous studies have documented reduced concentrations of tear components in reflex tears. The purpose of this study was to quantify tear total lipid concentration following acute use of the ITN.
55 dry eye subjects were enrolled in a single-arm study. Subjects used the ITN for approximately 3 minutes. Tear volume was assessed by tear meniscus height (TMH) captured by optical coherence tomography (OCT; Optovue RTvue), prior to and immediately following use of the ITN. Up to 10 µL of tears were collected using a capillary tube prior to and 5 minutes after use of the ITN. Total lipid concentration was determined using a modified spectrophotometric sulfo-phospho-vanillin reaction. All data are shown as mean±SD. Mean difference in OCT (post minus pre-stimulation) was analyzed using a paired t-test. Mean difference in total lipid concentration (post minus pre-stimulation) was evaluated by determining an equivalence margin and comparing the 95% confidence interval of the mean difference to the margin. P-values <0.05 were considered statistically significant.
Mean pre- and post-stimulation TMHs were 238.4±131.9 µm and 634.9±471.2 µm), respectively. The mean difference in TMH, 396.5±459.0 µm, representing a 166% increase in tear production following use of the ITN, was statistically significant (p<0.001). Mean pre- and post-stimulation lipid concentrations were 0.391±0.30µg/µL and 0.364±0.25µg/µL, respectively.An equivalence margin of ±0.078 µg/µL (20% of the pre-stimulation mean) was used to evaluate the equivalence of the pre and post-stimulation total lipid concentration. The 95% confidence interval of the mean difference in total lipid concentration (-0.016±0.18 µg/µL) fell within the equivalence margin [95% CI: -0.074, 0.042].
Use of the ITN resulted in a significant increase in tear volume with an equivalent concentration of total lipid as compared to a subjects basal tears. This finding suggests that neural stimulation results in more than simple reflex aqueous production.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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