To investigate the changes of the corneal microstructure of neurosurgically-induced neurotrophic keratitis patients compared to normal human corneas using in vivo confocal microscope (IVCM).

Ten eyes in the normal control group and 11 eyes in the neurosurgically-induced neurotrophic keratitis patient group were included in the present study. After corneal sensitivity tests were performed, thickness of each layer and number of endothelial cells and stromal keratocytes in the cornea were assessed using IVCM. Morphological characteristics of the corneal nerves were measured by ImageJ software.

After analysis of corneal thickness layer by layer, the Bowman's layer was significantly reduced in the neurosurgically-induced neurotrophic keratitis patient group compared with the normal control group ( p = 0.016) and the portion of Bowman's layer was significantly reduced in the neurosurgically-induced neurotrophic keratitis patient group compared with the control group ( p = 0.024). The nerve fiber length per square-millimeter became significantly shorter compared to the normal control group ( p = 0.042). The nerve fiber length per square millimeter showed significant correlations with the number of fibers, number of beading, branching patterns, and nerve tortuosity ( p = 0.002, 0.002, 0.013 and 0.034, respectively). The number of endothelial cells and stromal keratocytes, the number of nerve fibers and beading, and the pattern of branching and nerve tortuosity showed no significant differences between the normal and neurosurgically-induced neurotrophic keratitis patient groups.

Our results showed that decreased thickness of Bowman's layer may be related to the decreased corneal nerve distribution, secondary to the dysfunction of trigeminal nerve branch innervating the cornea. The microstructural changes of Bowman's layer can help diagnose the disease and evaluate the current status in neurosurgically-induced neurotrophic keratitis patients.