Confocal microscopy in vivo has dramatically improved our ability to evaluate the cornea in health and disease, contributing to a battery of imaging capabilities in ophthalmology. The technology has proven useful for quantitative and qualitative research in cross-sectional and longitudinal studies.
1,2 At a clinical level, however, uses of confocal microscopy have been limited to endothelial imaging, which can be more easily acquired with modern specular microscopes, and for diagnostic purposes in atypical microbial keratitis.
1,3 The latter is frequently considered as the only clinical application of confocal microscopy.
In this issue,
Misra et al.
4 describe a new potential clinical application of confocal microscopy in vivo that might prove to be valuable in the assessment of a common, systemic disease associated with significant morbidity: diabetes mellitus type 1. They measured corneal nerve parameters in type 1 diabetics and controls, and confirmed decreased subbasal nerve density and corneal sensitivity in diabetes. More importantly, they assessed the relationship between corneal neuropathy and systemic (autonomic and peripheral) neuropathy in diabetes and found evidence that corneal neuropathy might be an early indicator of diabetic neuropathy, even before electrophysiological tests become abnormal.
As the authors correctly discuss, further longitudinal studies are necessary to establish the temporal relationship between corneal nerve changes and the onset of diabetic neuropathy, and for determining the timing and role of corneal nerve examination in diabetic patients. Promising results from these studies will hopefully spur improvements in the ease of use of confocal microscopy in clinical practice. Misra et al.
4 should be congratulated for applying a corneal imaging technique to the study of a common systemic disease with potentially important implications.