Confocal microscopic examination of 40 corneas of 23 patients with
diabetes revealed the following morphologic characteristics. In four
patients we had data on only one eye, because patients were
uncooperative. The surface epithelium was normal in 36 of 40 eyes (
Fig. 2A ). We could not produce a sharp image for the evaluation of the surface
epithelium of both eyes of one patient, and, in addition, one cornea
showed focal areas of damaged epithelial cells
(Fig. 2B) . Another
patient was the only contact lens wearer in our study and showed
altered surface epithelial cells in one eye
(Fig. 2C) , which could have
been related to contact lens wear. However, the surface epithelium of
the fellow eye appeared normal. The basal epithelial cells were
considered to be normal in 35 of 40 eyes. No data were obtained in two
eyes. Two patients (the only eye of a patient with nephropathy and
severe neuropathy and both eyes of a patient with mild to moderate
neuropathy without nephropathy), however, had deposits in the basal
epithelial cells similar to that described in corneal dystrophies
(Fig. 2D) .
21 No corresponding abnormalities were observed by
biomicroscopy. Although the subbasal nerve morphology appeared normal
in 34 of 40 corneas, patients with diabetes had less nerve fiber
bundles
(Fig. 2E) than the healthy control subjects
(Fig. 2F) . One
patient had unusual curved nerve fiber bundles in the subbasal nerve
plexus in both corneas (
Fig. 3A ). Two patients had small particles between the nerve fiber bundles in
both eyes
(Fig. 3B) . We have proposed that these particles represent
Langerhans’ cells.
21 In 4 of 40 corneas, microfolds in
Bowman’s layer were observed. These microfolds were all in different
patients. The stromal keratocytes were normal in 34 corneas. Activated,
highly reflective anterior keratocytes and increased extracellular
matrix were noted in both corneas of two patients and one cornea of two
patients
(Fig. 3C) . Accumulation of highly reflective small
extracellular deposits was noted in one cornea. The stromal nerves
seemed normal in all patients in whom nerves were visualized
(Fig. 3D) .
However, in three patients no stromal nerves were observed in either
cornea. Confocal microscopy was not the proper method for evaluation of
corneal endothelial cells, because analysis of detailed morphology was
difficult in most corneas. Consequently, we did not evaluate the exact
morphology of the endothelial cells. In two eyes of different patients;
however, small endothelial pits were observed
(Fig. 3E) and folds in
the endothelial layer (or Descemet’s membrane) were seen in three eyes
(Fig. 3F) .