This study was to investigate the feasibility of frequency doubling technology (FDT) visual field testing in Alzheimer’s disease (AD) in order to identify early biomarkers of AD in patients already diagnosed with AD and compare the findings to participants not having Alzheimer’s disease. This biomarker would be useful in a battery of tests for the early identification of those with AD. It was not the intent to correlate the visual system biomarker with severity of disease, but to determine if the biomarker was present in pass or fail screening criteria. The study showed with very strong significance that the FDT can identify biomarkers of those with AD compared to an age-matched population that does not have AD. FDT is a simple test to take and administer and has been used to screen for eye and retinal diseases such as glaucoma, retinal macular degeneration, and diabetic retinopathy. The results obtained in the FDT readout are analyzed and compared to the age normative database within the system. The FDT ability to screen for AD biomarker in the visual system was significant in those with AD compared to the controls, and the deficits were not related to any ocular pathology. 1. Background The ability to detect light flicker and contrast sensitivity function is impacted early in diseases affecting visual system neural tissues such as in Alzheimer’s disease (AD), diabetic retinopathy, macular degeneration, and glaucoma. Light flicker and contrast sensitivity function reductions often occur before other visual processes are impacted in AD such as Snellen acuity. Screening tests that use either light flicker or contrast sensitivity or a combination of the two can be utilized to detect disease before it has resulted in substantial vision loss and before the vision loss impacts quality of life. In the case of AD, the use of such screenings of neurodegenerative processes affecting the visual system can also result in the timely and appropriate referrals in order to make diagnosis of a cognitive impairing disease. The frequency doubling technology visual field test (FDT) combines a stripe pattern light flicker and variable contrast target. The stripes that are variable contrast are vertical sine wave gratings of low spatial frequency (0.25？c/deg) that undergo counter phase flickering at a high temporal frequency of 25？Hz [1]. It is a simple test to take and to administer. The FDT is already used in eye screenings and is considered an important tool for the identification of eye disease and prevention of vision loss [2, 3]. The FDT has several programs internal
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