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B. Golebiowski, E. Papas, I. Jalbert, F. Stapleton; Corneal Innervation and Sensitivity During Contact Lens Wear . Invest. Ophthalmol. Vis. Sci. 2006;47(13):86.
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© ARVO (1962-2015); The Authors (2016-present)
Previous investigations have shown that changes in corneal sensitivity may be associated with altered morphology of the corneal sub–basal nerve fibre plexus. The purpose of this study was to investigate whether changes in corneal sensitivity during contact lens wear are accompanied by concurrent alterations in nerve fibre morphology.
27 long term extended wearers (13M:14F, mean age 40.1±6.9yrs, mean wear 13.5±4.7yrs) of low O2 transmissibility (Dk/t) soft contact lenses ceased lens wear for 1wk prior to refitting with high Dk/t silicone hydrogel lenses. Central corneal sensitivity was measured using the CRCERT–Belmonte aesthesiometer during low Dk/t lens wear, following 1wk of no lens wear, and after 6 and 12 mths of high Dk/t wear. In vivo images of sub–basal nerve fibres in the central cornea were captured at the same timepoints using a slit–scanning confocal microscope. Confocal images were analysed to obtain 7 indicators of nerve morphology: the total number of nerve fibre bundles (NFBs), NFB bifurcations and interconnections in each image, and the length, width, orientation and tortuosity of the longest visible NFB. Differences in nerve morphology over time and between wearing modalities were examined using mixed model or Friedman’s analysis of variance and Wilcoxon signed–rank tests, as appropriate. Bivariate correlations were carried out to investigate associations between nerve morphology and corneal sensation threshold.
Central corneal sensitivity demonstrated a significant reduction 1wk after low Dk/t lens wear was ceased (p=0.03) and remained diminished after transfer into high Dk/t lenses. No significant change was found to occur in any of the corneal nerve fibre morphology indicators investigated over the same timeframe. Group nerve morphology results across all time–points were as follows (mean or median values provided as appropriate): 4.7±1.8 NFBs, 2.0±1.5 NFB bifurcations and 0±0.5 NFB interconnections in each image; 316.1±72.4µm length, 4.1±0.7µm width, 6.4±20.4°T orientation and 2.0±0.5 grade tortuosity for the longest NFB in each image. No association was shown between nerve fibre morphology and corneal sensation threshold.
Changes in corneal sensitivity resulting from contact lens wear do not appear to be associated with changes in the indicators of nerve fibre morphology examined in this study. It is possible that contact lens wear induces changes in nerve morphology parameters other than those investigated, or that sensitivity change due to contact lens wear is not related to altered nerve structure.
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