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Alexis Ceecee Zhang, Jennifer P Craig, Laura Elizabeth Downie; Changes to corneal sensitivity precede symptoms of peripheral neuropathy in diabetes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3241.
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© ARVO (1962-2015); The Authors (2016-present)
The relationship between corneal nerve architecture and sensation is not well established. The aim of this cross-sectional clinical study was to investigate the relationship between central corneal sub-basal nerve plexus (SBNP) parameters and corneal sensitivity in people with diabetes, measured using non-contact corneal esthesiometry (NCCA).
Participants with diabetes (n=26) with no or mild peripheral neuropathy symptoms, and age-matched controls (n=15) underwent comprehensive ocular assessment, including NCCA (with stimuli at room temperature, ~23°C, and cooled, ~18°C) and in vivo corneal confocal microscopy. Central corneal SBNP parameters were quantified for corneal nerve fibre length (CNFL; mm/mm2), corneal nerve fibre density (CNFD; fibres/mm2), corneal nerve branch density (CNBD; branches on main fibre/mm2) and corneal nerve total branch density (CTBD; total branches/mm2). After normality testing, inter-group comparisons were analysed by a t-test or Mann-Whitney U-test, as appropriate. Correlations were assessed using Pearson’s correlation coefficient (r).
Corneal sensitivity thresholds were higher in the diabetes group compared with controls for room temperature (median [IQR]: diabetes: 0.60 [0.46-0.93] vs control: 0.28 [0.18-0.40] mBAR, p<0.0001) and cool stimuli (diabetes: 0.48 [0.36-0.58] vs control: 0.15 [0.10-0.28] mBAR). There were no significant inter-group differences for CNFL (diabetes vs control: mean±SEM: 12.61±0.63 vs 13.97±0.76 mm/mm2; p=0.19) or CNFD (diabetes vs control: 20.95±1.12 vs 23.44±1.54 fibres/mm2; p=0.19). The diabetes group had lower CNBD (23.66±2.08 vs 33.68±3.67 branches on main fibre/mm2; p=0.01) and CTBD (35.03±2.96 vs 49.62±5.49 total branches/mm2; p=0.01). In controls, there was no significant correlation between CNFL and corneal sensitivity thresholds to room temperature or cool stimuli (p>0.05). In the diabetes group, there was a moderate negative correlation between CNFL and corneal sensitivity thresholds to a cool stimulus (r=-0.44, 95%CI -0.71 to -0.05; p=0.03) but not to room temperature stimuli (r=-0.15, 95%CI –0.51 to 0.27; p=0.49).
Corneal sensitivity is reduced in people with diabetes who do not have significant peripheral neuropathy symptoms. The altered corneal structure-function relationship to cold stimuli in diabetes may indicate for disease-related effects on sub-population(s) of corneal nerves.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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