Sunday, January 17, 2010

10.10 Alzheimer's eye test


The headline of The Daily Mirror "High street eye test for Alzheimer's within five years" (Jan 14, 2010) is so tantalizing that prompts a further reading:

"A test for Alzheimer's could be carried out by shop opticians within five years. Scientists have found a way to detect the disease before any symptoms emerge during eye exams.

"By putting harmless fluorescent dye on the retina, they can spot dying cells - an early indication of Alzheimer's.

"The technique could end the need for costly MRI scans.

"Prof Francesca Coredeiro, of University College London, said: "Few people realise the retina is a direct, albeit thin, extension of the brain." and "It's entirely possible a visit to a high-street optician to check your eyesight in five years will also be a check on the state of your brain."

Wow, that is certainly progress; although a careful reading of the original research paper [here] raises some issues:

1. The high-street optician must own and be proficient in operating a confocal scanning laser ophthalmoscope to take the pictures of the retina through dilated pupils plus knowledge in interpreting the images;
2. To put the "harmless fluorescent dye on the retina" requires an intravenous injection of the dye, much like fluorescein angiography; the widely reported eye drops approach simply does not work; and
3. What evidence is there to support death and necrosis of the retinal photoreceptors in mice predates brain cell deaths, and even if true, does that apply to Alzheimer's in humans.

In five years? Maybe not.