Purpose: To measure subbasal nerve density and orientation in normal human corneas across a broad age range.
Methods: Sixty-five normal corneas of 65 subjects were examined by using tandem scanning confocal microscopy. Ages of subjects ranged from 15 to 79 years (mean 46 ± 19 years), with 5 subjects from each hemidecade. Subbasal nerve fiber bundles appeared as bright, well-defined linear structures in confocal images of the central cornea. Images from 3 to 8 scans per eye (mean 4.6 ± 1.8 scans) were randomly presented to a masked observer for analysis. The mean subbasal nerve density (total nerve length [μm] within a confocal image [area = 0.166 mm2]), the mean nerve number per confocal scan, and the mean nerve orientation were determined by using a custom software program. Correlations between age and nerve density and age and nerve orientation were assessed by using Pearson correlation coefficients.
Results: The subbasal nerve plexus was visible in the central cornea of all subjects. The mean subbasal nerve density was 8404 ± 2012 μm/mm2 (range 4735 to 14,018 μm/mm2). The mean subbasal nerve number was 4.6 ± 1.6 nerves (range 1 to 8 nerves). The mean subbasal nerve orientation was 94 ± 16 degrees (range 58 to 146 degrees). There was no correlation between age and subbasal nerve density (r = 0.21, P = 0.09) or between age and subbasal nerve orientation (r = −0.19, P = 0.12).
Conclusion: The density and orientation of the subbasal nerve plexus in the central human cornea does not change with age.
From the *Department of Ophthalmology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota; and †Department of Health Science Research, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota.
Received for publication August 11, 2004; revision received October 27, 2004; accepted November 6, 2004.
Supported in part by NIH Grant EY02037, Research to Prevent Blindness, Inc, New York, NY, and Mayo Foundation, Rochester, MN.
This paper was presented in part at the Association for Research in Vision and Ophthalmology, April 25-29, 2004, Ft. Lauderdale, FL.
Reprints: Jay C. Erie, MD, Mayo Clinic, 200 1st Street SW, Rochester, MN, 55905 (e-mail: firstname.lastname@example.org).