Alzheimer’s disease is widely reported to be associated with deficits in visual function. Visual disturbances include impaired stereopsis, contrast sensitivity and motion detection. Deficits specific to the magnocellular pathway (MGC) have been identified in Alzheimer’s disease. This article compares the visual field performances of patients with mild Alzheimer’s disease with normal control subjects. The authors detected visual field impairment attributable to the magnocellular pathway using frequency doubling technology – Matrix (FDT-Matrix). The FDT Matrix perimetry is based on an illusion occurring when a grating of low spatial frequency undergoes counter-phase flicking and measures contrast sensitivity. The process selectively tests the function of the MGC pathway. The authors suggest that testing the response of the MGC pathway using this method may be a sensitive method of detecting a field defect. Patients with Alzheimer’s disease took significantly longer to perform the test than controls. There were statistically significant differences in mean deviation and pattern standard deviation values between the two groups. The results imply that the pathogenesis of cognitive decline may be present in the magnocellular pathway, as well as the cortical area, in Alzheimer’s disease. FDT testing may be a useful test for early identification of Alzheimer’s disease, as well as for follow-up of these patients, especially when visual field testing is unreliable due to cognitive impairment. Further studies are required to further explore the source of visual field loss in 
this patient group, as well as the clinical usefulness of FDT testing.

Screening for patients with mild Alzheimer’s disease using frequency doubling technology perimetry.
Aykan U, Orcun Akdemir M, Yildirim O, Varlibas F.
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Claire Howard

Salford Royal NHS Foundation Trust, Salford, UK.

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