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Eye scan shows first sign of Alzheimer's disease

09 Oct 2006

Scanning the lens of a human eye with infrared laser light can reveal the earliest signs of Alzheimer's disease in a matter of seconds, according to US start-up Neuroptix. Matthew Peach speaks to the firm's chief executive officer, Paul Hartung, about the technology.

Neuroptix has developed an optical technique for early diagnosis of Alzheimer's disease (AD) – the degenerative illness that is becoming a growing problem as the population is always getting older as people are living longer. Instead of having to wait until a patient shows signs of mental degeneration, Neuroptix's optical technique can indicate the likely onset of the disease many years earlier, giving a patient time to make adjustments to lifestyle, diet and exercise, which could improve their chances of avoiding the worst aspects of this currently incurable disease.

The Neuroptix system, known as the QEL 2400, measures the presence of telltale amyloids in the lens of the eye with a combination of dye treatment and scanning by an infrared laser. OLE interviews Paul Hartung, president and chief executive officer of Neuroptix, about the technology.

OLE: What are the origins and objectives of Neuroptix's work into early diagnosis of AD?

PH: Neuroptix was founded in 2001 following the breakthrough discovery by our company founder Lee Goldstein at Harvard Medical School. He discovered that beta amyloid proteins, which create plaque in the brain of patients suffering from AD, can also be identified in the lens of the eye. Our objective is to develop and commercialize a non-invasive eye test for early diagnosis of AD.

Why are you focusing on AD?

AD is now the eighth most common cause of death (in the US). But this does not represent the true scale of the problem because AD sufferers often die from other causes. It is also believed that as we get older the likelihood of getting this disease increases. It is a devastating illness not only for the victims, but also for their families. There is a great need for diagnostics to detect the disease at an early stage and to enable effective treatment. Pharmaceutical companies need more sensitive diagnostics to striate subjects in clinical trials and to measure the efficacy of their new therapies.

What is Neuroptix's test set-up?

Eye drops are applied that contain a fluorescent ligand (dye), which is temporarily absorbed by the lens and binds to amyloid proteins. A low-power class I laser scans the lens, exciting the fluorescent dye and scattering off the protein aggregates. The fluorescent dye provides the biochemical specificity, identifying the type of protein. Using a technique called quasi-elastic light scattering, we are able to quantify the size of the protein aggregates. We can make a judgment on the likelihood of the patient becoming an AD sufferer based on the light measurements and post-processing that data using our software.

In the late stages of the disease, the aggregates in the lens become so dense that they are visible in the supranucleus of the lens. Our technique is essentially a molecular diagnostic technique, with the ability to take measurements on a clear lens. Pre-clinical testing has shown that it is sensitive enough to pick up amyloids in the eye before plaque forms in the brain.

What is the test timescale?

The test takes a matter of seconds; it is done within the timeframe of a normal physical exam. It is similar to, but much less invasive than, a retinal scan and the equipment is similar to a laser-scanning ophthalmoscope.

How do you differentiate AD from other diseases detected this way?

Our dye agent provides the biochemical specificity of indication for AD. In addition, there is anatomical specificity based on the location of the aggregates in the supranucleus of the lens. We are focused on AD but we believe that it could be applied to prion diseases. For example, the US Department of Agriculture is testing this technique to assess prion-affected deer, sheep etc, using Neuroptix's dyes to achieve rapid screening.

What are the limitations of other AD diagnosis methods?

Clinical diagnosis generally occurs in the later stages of the disease, based on psychoanalysis and other factors. The new tests that are in development include:

  • Cerebrospinal fluid tests. This requires an invasive and complication-prone spinal tap and is not sensitive enough to detect AD;
  • Brain scans (MRI and PET). These are expensive and are only of use in the later stages of the disease. Neuroptix's technique will be a feeder technology for these more expensive tests;
  • Blood tests. These can only determine genetic predisposition in some cases;
  • Urine tests. These have been rejected by the Food and Drug Administration. They are not sensitive enough and have highly variable results.

How is the Neuroptix's technique an improvement on existing methods?

To date there has been no in vivo commercial biomarker for AD. The "gold standard" so far has been the mental analysis of a patient, but by the time that diagnosis is made, the patient has typically lost 50% neural function – an irreversible state of brain damage. We can identify the disease prior to any cognitive signs developing. Therefore, our aim is to diagnose the condition prior to any brain damage occurring.

The potential applications of our technique will be as an early confirmation test for AD in those who present with mental problems and eventually as a preventative AD check-up technique.

How can an optics-based assessment help in this endeavour?

Optics-based techniques are suitable for non-invasive measurement of biophysical changes to the eye. The methods that we are developing are non-contact, sensitive, fast and relatively inexpensive.

What have you achieved in terms of developing this method?

Initial work has been done using human cadavers. A preclinical version of the system has been developed and results show that the technology is sensitive and can identify amyloid pathology in the eye at a very early stage in the disease. Clinical prototypes have been developed, which are safe for human use, and it has been proven that in vivo measurements can be performed.

How is this a significant medical breakthrough and will it save lives?

This is a major medical breakthrough. Around 4.5 million people in the US are already diagnosed with AD, with care costs alone estimated to be $100 bn per year. The number of sufferers is growing as people are living longer. The opportunity to catch the disease prior to cognitive loss, and to enable early treatment, is enormously significant.

Are there any existing medical techniques to counter AD?

There are drugs available today that work for some patients but they are prescribed at a much later stage in the disease than that which we are identifying. There are also recommended lifestyle changes, including better diet and physical and intellectual exercise.

On the drug development front, I have to say that AD therapeutic development is a high priority for large pharmaceutical companies. There are more than 500 possible solutions currently under development that are expected to be fundamentally different from what is available today. At Neuroptix, we believe that in the next three years or so there will be better drugs available.

What are the next stages of development and are there any technical or financial barriers?

The next stage of development will be the creation of instruments for clinical trials and the safety testing of the fluorescent ligands for human use. Neuroptix has already raised $1 m through non-exclusive big pharmaceutical R&D funds and "angel" investors. We are seeking to raise series A equity financing in 2006. We are developing partnerships with large pharmaceutical companies interested in using the technology as a drug-development tool. We are also developing partnerships with medical-equipment and diagnostics companies to support development, manufacturing and worldwide commercialization.

• This article originally appeared in the October 2006 issue of Optics & Laser Europe magazine.

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