Bill Harvey: Days of future past
Author: Bill Harvey
Evidence continues to build regarding the measurement of changes in the eye as a predictor of dementia states and loss of cognitive function.
Last year, there was great interest in the announcement that Optos was teaming up with the company Amydis in developing retinal screening for Alzheimer’s disease. Amydis has developed a technique that allows visualisation of the build up of amyloid, a useful biomarker for the disease which is found in the retina in increasing amounts. When made to fluoresce, the amyloid can be detected by ultra-wide field scanning laser ophthalmoscopy (as offered by Optos systems) and so can prove a useful biomarker for the early detection of the disease.
More recently, a number of different methods of early detection have been hinted at. A paper in the latest issue of the American Journal of Ophthalmology has shown that postmenopausal women with larger cup-to-disc ratios (≥0.6 in either eye) but without diagnosed glaucoma or ocular hypertension have poorer cognitive functioning than women with smaller cup-to-disc ratios. Though much further research will be needed, this is an interesting finding linking disc appearance (as measured during any eye check) with dementia.
Also, the widespread use of spectral domain OCT continues to throw out useful data. A new study, also from the US, has found that there is a measurable and significant increased macular thickness in patients with dementia and suggests that this parameter (and not changes to the retinal nerve fibre layer thickness) may usefully indicate early neurodegeneration as occurs with dementia states.
So what? Some argue that early detection of dementia has no useful function. Figures from the US suggest otherwise, with predictions of long-term care cost savings of many trillions where the disease is detected early.
Readers investing in OCT and SLO technology might want to keep an eye on this future potentially important role of their kit.