An Australian optometrist researching how contact lenses affect the eye accidentally discovered a new way to study diabetic neuropathy. The discovery holds the key to monitor nerve degeneration over time.
The extreme magnification of a special microscope, called a corneal confocal microscope, allowed Nathan Efron, a professor at the Queensland University of Technology’s School of Optometry at Brisbane, Australia, to see fine nerves in the cornea that had never been seen before.
Efron found that the nerves affected by neuropathy are an exact match to nerves found in front of the eye, and is testing whether looking at their level of degeneration in these nerves over a period of time would match the nerve degeneration found in arms and legs.
“We want to see how well the degeneration of the nerves in the cornea matches the degeneration of nerves throughout the body, and if it matches it will mean that we can monitor diabetic neuropathy using a simple eye test,” Efron says.
The breakthrough is so profound and important that Efron was honored last November with the Glenn A. Fry Lecture Award from the American Academy of Optometry for his research into non-invasive ophthalmic diagnosis of diabetic nerve damage.
As the principal researcher of a five-year study ‒ Expanding the Role of Optometry in Diabetes Management: Determining the Discrimination Capacity of a Novel New Ophthalmic Marker of Diabetic Neuropathy ‒ Efron says early indications are promising and he is presenting his findings at the Asia Pacific Academy of Opthamology Congress in Sydney this week.
When he first saw the nerves, Efron, who has type 2 diabetes, knew at once that what he was seeing was something unique. One of the serious consequences of the disease is diabetic neuropathy – a condition that causes nerve damage and can result in ulcers and amputations ‒ that affects about half of diabetics in varying degrees of severity, which causes the degeneration of nerves, mostly in the arms and leg. (See my post ‘Don’t Ignore Diabetic Nerve Pain’ here.)
“I wondered if my own diabetes specialist might be interested in the technology and it turned out he was a world authority on diabetic neuropathy. He thought it was astonishing,” recalls Efron. It was ideas generated by discussions with his diabetes specialist that led Efron to investigate linkages between the nerves in the eyes and nerves elsewhere in the body with the aim of developing a relatively simple and non-invasive eye test to identify neuropathy (or diabetic nerve disease).
Neuropathy is typically measured by taking skin biopsies from the foot and running a series of specialized tests that can take up to a week to complete. In many cases, this debilitating condition is not identified until serious, and irreparable, damage has already been done.
On the other hand, the quick and non-invasive eye tests would see results in a matter of minutes. In short, the importance of Efron’s discovery lies in the fact that since the eye is a transparent structure, it is the only place in the body where you can look directly at nerves and their degeneration over time.
Efron and his team have established a four-year clinical trial assessing the optimal method of ophthalmic neuropathy diagnosis. This will hopefully lead to a standard protocol for optometrists and ophthalmologists to quickly and simply identify people at risk of neuropathy, anticipate the level of damage and assess treatment outcomes.
There are multiple benefits of being able to measure the onset of neuropathy, one being that there are drugs in development that aim to cure diabetic neuropathy. “When these drugs are ready to come onto the market, we will, using our method, be able to detect nerve degeneration early and then hopefully cure it,” he says.
For the tests, patients would receive a drop of anesthetic in the eye, then a corneal confocal microscope would capture a 20 second “movie” of their eye for analysis.
There are also three more tests being looked at – the first, called non-contact corneal aesthesiometry, measures how nerve degeneration is affecting the function of the cornea, by projecting tiny puffs of air into the eye, growing progressively stronger until the patient can feel it.
Two more eye tests will look at the effect of nerve degeneration on the retina.
“Diabetic patients currently go for yearly eye tests anyway, so we are saying that these tests could be done at the same time, and only take a few minutes,” Efron says.
Efron hopes his discoveries will lead to early testing for diabetic neuropathy that will motivate sufferers to better manage their disease. Testing could be carried out at the same time as diabetes patients are tested for other eye problems caused by the disease.
The test has been used to monitor nerve regeneration in patients who have undergone kidney and pancreas transplants, and it could help track the effects of new treatments.
Based on a news report in Sunday Star Times