Abnormal Anterior Corneal Morphology in Diabetes Observed Using In Vivo Laser-scanning Confocal Microscopy

To assess if diabetes alters corneal epithelial, anterior stromal and subbasal nerve plexus morphology and to determine the associations between these and other clinical variables.

A cohort of 78 participants with diabetes (39 with Type 1 and 39 with Type 2 diabetes) and 29 age-matched healthy controls underwent laser-scanning confocal microscopy of the central cornea. Intermediate cell density (ICD), basal cell density (BCD), anterior stromal cell density (ASCD), corneal nerve fiber density (CNFD) and nerve fiber length (CNFL) were quantified.

Compared with controls, participants with diabetes showed reduced ICD (6097 ± 669 vs. 5548 ± 669 no/mm², P<.01), BCD (8925 ± 1196 vs. 7842 ± 1040 cell/mm², P<.01), CNFD (23.4 ± 9.1 vs. 17.5 ± 9.7 no/mm², P<.01) and CNFL (21.0 ± 4.0 vs. 17.4 ± 4.9 mm/mm², P<.01), with no difference in ASCD (785 ± 262 vs. 733 ± 278 cell/mm², respectively, P=.40). None of these structural parameters were associated with type of diabetes (P>.06). Multiple regression analysis showed that ICD and BCD were inversely associated with the diabetes duration and diastolic blood pressure (P<.05) and positively associated with CNFD (P<.01). CNFD and CNFL were inversely associated with HbA_1c (P<.01), while ASCD was inversely associated with age (P<.01).

Corneal epithelial cells and subbasal nerve fibers are reduced in patients with diabetes; however, anterior stromal cells show no difference. Furthermore, abnormalities in corneal epithelial cells and nerves are interrelated and correlated with modifiable risk factors.