Corneal Confocal Microscopy to Assess Diabetic Neuropathy: An Eye on the Foot

Abstract

Accurate detection and quantification of human diabetic peripheral neuropathy are important to define at-risk patients, anticipate deterioration, and assess new therapies. Easily performed clinical techniques such as neuro-logical examination, assessment of vibration perception or insensitivity to the 10 g monofilament only assess advanced neuropathy, i.e., the at-risk foot. Techniques that assess early neuropathy include neurophysiology (which assesses only large fibers) and quantitative sensory testing (which assesses small fibers), but they can be highly subjective while more objective techniques, such as skin biopsy for intra-epidermal nerve fiber density quantification, are invasive and not widely available. The emerging ophthalmic technique of corneal confocal microscopy allows quantification of corneal nerve morphology and enables clinicians to diagnose peripheral neuropathy in diabetes patients, quantify its severity, and potentially assess therapeutic benefit. The present review provides a detailed critique of the rationale, a practical approach to capture images, and a basis for analyzing and interpreting the images. We also critically evaluate the diagnostic ability of this new noninvasive ophthalmic test to diagnose diabetic and other peripheral neuropathies.

Associations between Sensorimotor, Autonomic and Central Neuropathies in Diabetes Mellitus

“…Quantitative sensory testing are limited by involvement of larger fibres, however the more objective assessments including skin biopsies quantifying nerve fiber density or corneal confocal microscopy, are limited to specialized centers [9][10][11]. Diabetic autonomic neuropathy shares same etiology as peripheral neuropathy.…”

Diabetinės neuropatijos problema ir gydymo ypatumai

“…It was concluded that the frequency of DN in the patients with type 1 diabetes is 77. 4 Conclusions. Leg polyneuropathy is the most common in both groups.…”

Treating Diabetic Neuropathy: Present Strategies and Emerging Solutions

“…The Toronto group highlighted the role of a multi-pronged approach that should consider signs or symptoms supported by neurophysiological studies and quantitative sensory testing [8]. Although nerve conduction studies are commonly advocated to confirm the diagnosis of DPN, and to assess its progression or regression in a clinical research setting, they may not detect the earliest nerve fiber damage, and only test a minority of nerve fibers, namely the large myelinated fibers [19,20]. However, pain, temperature, autonomic function, and wound pathophysiology are largely dependent on small nerve fibers [21].…”

“…Newer techniques assess these small nerve fibers, and thus represent an intuitively attractive paradigm. Two such techniques include the visual quantification of intra-epidermal nerve fibers through skin biopsy and corneal confocal microscopy, which allows non-invasive in-vivo imaging of corneal nerves [19,22].…”