A simple eye test with a high powered microscope can be used to diagnose or monitor nerve damage resulting from diabetes – the most common cause of foot ulcers and amputations.
Using the corneal confocal microscope, researchers have now demonstrated that the shape and function of nerve fibres in the cornea can reflect the extent of diabetic neuropathy elsewhere in the body.
Professor Nathan Efron, School of Optometry, Queensland University of Technology (QUT), said diabetic neuropathy affects up to half of all people with diabetes and is currently assessed by a battery of sensory tests, nerve conduction measurements or tissue biopsies.
“The eye is a transparent structure and there is nowhere else in the body where you can look directly at nerves.
“We’ve found we can correlate visual evidence of nerve degeneration in the cornea with the severity of peripheral neuropathy,” he added.
A recently published study of 100 patients with diabetes found corneal nerve fibre density, nerve fibre length and nerve branch density all decreased significantly with increasing neuropathic severity.
Speaking at the Asia Pacific Academy of Ophthalmology (APAO) Congress, Professor Efron said the test has also been used to monitor nerve regeneration in diabetic patients with severe disease following combined kidney and pancreatic transplants.
A $5 million longitudinal study currently underway at QUT and the University of Manchester in the UK will provide more data on how accurate the test is, how early diabetic neuropathy can be detected and the rate of nerve degeneration in diabetic neuropathy.
“While there is no cure or medication for diabetic neuropathy, early detection gives patients additional motivation to get their diabetes under better control and reduce the risk of complications such as diabetic foot ulcers,” Professor Efron said.
“Ultimately we could also use this technique to test new therapies for neuropathy as they become available,” he added.
Professor Efron said that while the technique is still largely a research tool, it has immediate clinical applications.
“I’m thinking it will be possible to add in this test, as a sensitive and specific early measure of diabetic neuropathy, to the regular eye checks for diabetic retinopathy,” he added. “This will mean an expanded role for the ophthalmic professions in the detection of diabetic complications.”