Vision Screening of Alzheimer's Disease With Frequency Doubling Technology (FDT)

Abstract

Abstract: : Purpose: Individuals with Alzheimer’s disease (AD) have deficits in visual function including spatial frequency contrast sensitivity. The Frequency Doubling Technology is an efficient screening tool for functional losses when there are cognitive impairments. This project investigated its application in indivduals with AD. Methods: The FDT measures low spatial frequencies and tests the central 20 degrees of the visual field. It is similar to a traditional visual field in that individual's respond when they see a target. The instrument is thought to isolate a subset of retinal ganglion cells in the magnocellular pathway by use of low spatial frequency sinusoidal gratings (<1 cycle/degree) that undergo a high temporal frequency counter–phase flicker at 15 Hz or greater. We have conducted a preliminary study with five patients with AD and five age–matched healthy elderly participants. All ten individuals were free of any ocular pathology. Results: The five patients with AD, but none of the control group showed deficits on the FDT. The FDT appears to be sensitive to AD–related changes in visual function that are not obvious from standard ocular examination. Conclusions: Further studies are warranted to determine if the deficits are the result of under–diagnosed glaucoma in AD or if the measured deficits are unique to AD.

Keywords: aging: visual performance • contrast sensitivity • neuro–ophthalmology: cortical function/rehabilitation