Abstract
Purpose: :
Movement disorders affect 40 million Americans. The ratio for these disorders is one in seven, which is twice the number of those with diabetes. Such disorders affect motor control and can impact the visual system. We proposed to determine if the visual field threshold test; Frequency Doubling Technology (FDT) would identify deficits in the patients presenting in a movement disorder neurology clinical practice. The specific movement disorders screened for in this study included; Parkinson’s disease, Presumed Lewy Body disease and Huntington disease.
Methods: :
Patients presenting for care in the movement disorder clinic were invited to participate in a vision screening that included a brief visual history, distance acuities and FDT. The FDT is believed to have the capacity to isolate retinal ganglion cells in the magnocellular pathway by utilizing a low spatial frequency sinusoidal grating (<1 cyc/degree) that undergoes a high temporal frequency counter phase flicker at 25 Hz or greater. Backlit flashed images are viewed on a fixed, flat, shielded screen in front of a stationary subject. The patient perceives the targets as small, striped square-shaped areas in either central or peripheral vision.
Results: :
Deficits were identified in clinical patients with movement disorders of Huntington disease, Parkinson's disease, and Presumed Lewy Body disease. The example included is the FDT result from the right eye of a young adult patient with Huntington disease.
Keywords: neuro-ophthalmology: diagnosis • visual impairment: neuro-ophthalmological disease • quality of life