Corneal nerve structure and function in keratoconus: a case report.

PURPOSE: To investigate corneal nerve structure and function in a 24-year-old patient with keratoconus and prominent corneal nerves.

METHODS

Corneal nerve appearance was assessed by using a corneal confocal microscope, and corneal nerve function was assessed by using a Cochet-Bonnet aesthesiometer. Findings were compared to those of an age-matched control subject without keratoconus.

RESULTS

The patient with keratoconus was found to have thicker nerve fiber bundles in the stroma (keratoconus vs. control, 9.8 +/- 5.0 microm vs. 5.4 +/- 2.7 microm) and reduced nerve fiber density in the subepithelial plexus (keratoconus vs. control, 269.7 +/- 145.6 microm vs. 1,258 +/- 254.8 mum) compared to the control subject. The patient with keratoconus was found to have reduced corneal sensitivity compared to the control subject (keratoconus vs. control 0.39 gr/mm2 vs. 1.59 gr/mm2).

CONCLUSIONS

Corneal confocal microscopy proved to be a useful in vivo technique for assessing corneal nerve structure in this patient with keratoconus. Although the total number of stromal nerve fiber bundles was reduced in the patient with keratoconus versus the control subject, the increased tortuosity and increased nerve fiber diameter may explain why the corneal nerves appear more visible in this patient with keratoconus.