Macular Measurements May Spot Visual Defects in Alzheimer's

By David Douglas

April 04, 2017

NEW YORK (Reuters Health) - Changes in the retina of patients with Alzheimer's disease (AD) appear to be associated with visual dysfunction, according to Spanish researchers.

As Dr. Maria Satue told Reuters Health by email, "Our study found detectable changes in retinal parameters using imaging technologies in ophthalmology, which were associated to visual alterations in these patients, such as visual acuity and color vision alterations."

In a paper online March 10 in Eye, Dr. Satue of Hospital Universitario Miguel Servet, Zaragoza, and colleagues note, “Although AD is most commonly associated with memory deficits and cognitive impairment, patients with AD also exhibit alterations in sensory perception, such as visual processing.”

To investigate, the team studied 24 patients with AD and 24 controls. Spectral domain-optical coherence tomography was used to make structural measurements of the retinal nerve fiber layer (RNFL) and macular thickness.

Contrast sensitivity vision was generally significantly worse in patients than controls and was the functional parameter most strongly correlated with structural measurements.

Compared with controls, macular thinning was seen in all sectors except the fovea, and the RNFL exhibited both significant thinning in the superior quadrant and lower average thickness.

Color vision was also significantly affected and was strongly associated with macular volume. Visual acuity at different levels of contrast was associated with macular and RNFL thickness.

The researchers point out, "Further studies including the analysis of the retinal ganglion cell complex would be needed to better understand the physiopathology of visual impairment in AD patients" and to determine the utility of these and other visual tests "as a biomarker of severity and progression in AD."

Dr. Satue added, "These exploratory techniques are innocuous, fast and relatively cheap, and provide important information that may be used as a tool for diagnosis and monitoring progression of Alzheimer's disease."

Dr. Antonio Curreri, chairman emeritus of the department of ophthalmology at Cabrini Medical Center in New York, told Reuters Health by email that the study "makes an attempt to correlate AD with retinal change. The authors have discovered both visual and color change associated with a physical change in the retina, which apparently has not been previously described."

"While there are changes," said Dr. Curreri, "they make no mention of the sensitivity or the specificity of these changes. One can find similar changes in many systemic disease.”

"These are very interesting findings," he concluded, "but I believe that still more studies are required to advance any clinical care."

SOURCE: http://bit.ly/2nO9FLG

Eye 2017.

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