Purchase this article with an account.
Maria Markoulli, Luisa Holguin Colorado, Katie Edwards; Corneal nerve morphology and its association with inflammatory mediators and neuropeptides in the healthy tear film. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1808.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
A potential interaction has been described between the immune and nervous systems. This study aims to determine whether the concentration of tear film inflammatory mediators and neuromediators are associated with corneal nerve morphology in healthy individuals.
Flush tears were collected from 21 healthy participants aged 39.7 ± 9.9 and analyzed for total protein content (TPC), substance P, matrix-metalloproteinase-9 (MMP-9), tissue inhibitor of MMPs-1 (TIMP-1), tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6). In vivo confocal microscopy was performed using the Heidelberg Retinal Tomograph III with the Rostock Corneal Module (Heidelberg Engineering GmbH, Heidelberg, Germany) on one eye. Variables measured were corneal nerve fiber length (CNFL), density (CNFD), branch density (CNBD), fiber tortuosity (CNFT), fiber total branch density (CTBD), fiber area (CNFA), and fiber width (CNFW). For each variable, the average, high and low values were analyzed. Pearson’s correlation analysis was performed to test for associations.
CNFW-average correlated with IL-6 (r = -0.58, p = 0.01), CNFW-low correlated with TPC (r = -0.50, p = 0.04) and CNFW-low correlated with IL-6 (r = -0.57, p = 0.02). The MMP-9:TIMP-1 ratio correlated with CTBD (r = 0.61. p = 0.02). When each protein was considered as a percentage of TPC, MMP-9 correlated with the standard deviation of CNFD (r = 0.60, p = 0.02), TNF-a correlated with CTBD (r = 0.58, p = 0.02), IL-6 correlated with CNFW-average (r = -0.57, p = 0.02) and IL-6 correlated with CNFW-low (r = -0.58, p = 0.02). Tear flow-rate correlated with TPC, Substance P and IL-6 (r = 0.52, p = 0.04; r = 0.67, p = 0.001; and r = 0.54, p = 0.03, respectively). Substance P correlated with TPC and IL-6 (r = 0.65, p = 0.02 and r = 0.52, p = 0.03, respectively).
Both inflammatory mediators and neuromediators correlated with measures of corneal nerve morphology, supporting the link between the inflammatory and nervous systems. The corneal nerve thickness in particular showed a negative correlation with inflammatory mediators. The correlation between tear flow-rate and protein concentrations indicates that flow-rate should be monitored as this may influence the outcome.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
This PDF is available to Subscribers Only