Fluorescence Detects Alzheimer’s Indicators in the Eye

Two fluorescence imaging approaches can find traces of plaque associated with Alzheimer’s disease in the eye, presenting possible opportunities for early intervention.

Two companies — NeuroVision Imaging LLC of Sacramento, Calif., and Cognoptix Inc. of Acton, Mass. — announced their findings this week at the Alzheimer’s Association International Conference in Copenhagen.

NeuroVision said preliminary results from 40 patients showed that beta-amyloid levels imaged in the retina were significantly correlated with beta-amyloid levels in the brain that appeared using positron emission tomography (PET). The retinal amyloid imaging test differentiated between Alzheimer’s and non-Alzheimer’s subjects with 100 percent sensitivity and 80.6 percent specificity, the company said.

Retinal plaque was detected using a camera with 20-µm resolution and curcumin fluorescence imaging. Patients ingested high-bioavailability curcumin — a component of the spice turmeric that binds to beta-amyloid — prior to imaging.

Preliminary testing showed an average of 3.5 percent increase in retinal amyloid over a 3.5-month period, the company said. Further testing on 200 patients in Western Australia is expected to be complete by the end of the year.

“If longitudinal studies demonstrate that our test can detect changes in retinal plaque over a short period of time, we see great potential for using the technology not just for early detection, but also for measuring response to therapy,” said NeuroVision CEO Steven Verdooner.

Current methods to detect brain amyloids, such as PET and analysis of cerebral spinal fluid are invasive, expensive and not conducive to repeated tests, Verdooner added.

The clinical trial is a collaboration of the Commonwealth Scientific and Industrial Research Organization, Edith Cowan University, McCusker Alzheimer’s Research Foundation and NeuroVision and is part of the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing.

Meanwhile, Cognoptix has used fluorescent ligand eye scanning to detect beta-amyloid in the lens of the eye. The technique involves a topically-applied ointment that binds to amyloid and a laser scanner.

The company said it conducted a feasibility study involving 20 people with probable Alzheimer’s and 20 age-matched healthy volunteers, and was able to differentiate Alzheimer’s patients a sensitivity of 85 percent and specificity of 95 percent.

PET scans were also performed to compare plaque density in the brain, which correlated with the lens results, the company said.

For more information, visit www.neurovisionimaging.com and www.cognoptix.com.