Predicting peripheral neuropathy in diabetes via novel eye scan

Corneal confocal microscopy (CCM) has been found to predict peripheral neuropathy in patients with type 1 diabetes, according to a recent study.

The new, noninvasive test involves examination of unmyelinated nerve fibers at high magnification while using a laser-scanning corneal confocal microscope to image the subbasal nerve plexus of the patient’s cornea, according to Medscape.

The study-published online in Diabetes Care-was conducted to determine if deficits in corneal nerve fiber length assessed using CCM could predict future onset of diabetic peripheral neuropathy. 

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The researchers compared corneal nerve fiber length and various other baseline measures between 90 nonneuropathic patients with type 1 diabetes who did and did not develop diabetic peripheral neuropathy after 4 years. The receiver operator characteristic curve was used to determine the ability of single and combined measures of neuropathy to predict diabetic peripheral neuropathy.

Previous studies demonstrated utility for CCM in assessing peripheral diabetic neuropathy, autonomic neuropathy, and neuropathy in those with prediabetes, Medscape reported.

In this current study of 90 patients, CCM was found to be able to detect the 4-year incidence of diabetic peripheral neuropathy with 63% sensitivity and 74% specificity for a corneal nerve fiber length threshold cutoff of 14.1 mm/mm².

The researchers concluded that diabetic peripheral neuropathy could be predicted by various demographic, metabolic, and conventional neuropathy measures.

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Though Andrew G. Lee, MD, Ophthalmology Times Editorial Advisory Board member, was excited about the findings, he expressed some hesitation, saying more tests need to be done to validate the results.

“While this is an important preliminary finding, more work needs to be done to improve the technology and the relatively modest sensitivity and specificity of CCM before it can be used clinically for relatively high-stakes decision-making,” said Dr. Lee, chairman, Department of Ophthalmology, Houston Methodist Hospital. “Although CCM is non-invasive, objective, fast, and reproducible, the validity of the technique against a gold standard has not been completely established.”

The cost and cost-effectiveness of the eye scan in a clinical setting needs to be validated as well, Dr. Lee said.

“Nevertheless, CCM is an exciting new tool in the fight against diabetes and its disabling sequelae,” he concluded.