Three different eye tests developed by researchers have shown promise in diagnosing Alzheimer’s disease. One recent study in the UK measured patients’ eye responses to light. An Australian study reported at an Alzheimer’s disease conference in 2011 measured patients’ differences in the width of certain retinal blood vessels. In Massachusetts, studies by researchers in 1995 showed differences in patients’ pupil dilation when eye drops were added.
Eye Tracking Measurement Study in the UK
Researchers from Lancaster University in the UK reported this month on a study that showed Alzheimer’s patients have errors in following light with their eyes compared to a control group. The study also showed that for those already diagnosed with Alzheimer’s, their inability to do the test was linked with lower memory function. The researchers studied 18 people with Alzheimer’s disease, 25 patients with Parkinson’s disease, 17 healthy young people and 18 healthy older people. The study participants were asked to follow the movement of light on a computer monitor. Eye tracking measurements then were taken in detail. The patients with Alzheimer’s responded correctly when looking toward the light, but were unable to respond correctly when asked to look away from the light.
Australian Study of Retinal Blood Vessels
Researchers from Australia’s national science agency, CSIRO, measured the width of certain blood vessels in the retina of people that were healthy, those with Alzheimer’s disease and those patients who had only mild cognitive impairment. There were 110 people in the healthy group, 13 people in the Alzheimer’s group and 13 people in the mild cognitive impairment group. The retinal vessels’ width of the patients with Alzheimer’s were found to be significantly different than those in the other two groups. The amount of difference correlated with the amount of plaque seen in the patients’ brains.
US Study of Pupil Dilation
Harvard University Medical School and Brigham and Women’s Hospital showed through studies in 1995 that there were significant differences when pupil dilation was measured in response to eye drops in Alzheimer’s patients versus non-Alzheimer’s patients. The 19 patients with Alzheimer’s disease had exaggerated pupil dilation when a drop of tropicamide was added to an eye as compared to 32 individuals without the disease.
All of the studies noted had small sample sizes of Alzheimer’s patients. Nevertheless, it seems clear that there are a variety of eye differences that can be measured which distinguish Alzheimer’s patients from non-Alzheimer’s patients.
Sources: www.telegraph.co.uk 8/26/2012
www.hms.harvard.edu Spring 1995