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Identification and treatment of the visual processing asymmetry in MS patients with optic neuritis: The Pulfrich phenomenon
Journal article   Open access   Peer reviewed

Identification and treatment of the visual processing asymmetry in MS patients with optic neuritis: The Pulfrich phenomenon

Millad J Sobhanian, Rohit Agarwal, Ethan Meltzer, Eric Kildebeck, Benjamin S Frohman, Ashley N Frohman, Steven L Galetta, Shiv Saidha, Owen White, Pablo Villoslada, …
Journal of the Neurological Sciences, Vol.387, pp.60-69
04/15/2018
DOI: 10.1016/j.jns.2018.01.029
PMID: 29571874

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Abstract

The Pulfrich phenomenon (PF) is the illusory perception that an object moving linearly along a 2-D plane appears to instead follow an elliptical 3-D trajectory, a consequence of inter-eye asymmetry in the timing of visual object identification in the visual cortex; with optic neuritis as a common etiology. We have designed an objective method to identify the presence and magnitude of the PF, in conjunction with a cooresponding strategy by which to abolish the effect; with monocular application of neutral density filters to the less affected fellow eye, in patients with MS and a history of optic neuropathy (e.g. related to acute optic neuritis or subclinical optic neuropathy). Twenty-three MS patients with a history of acute unilateral or bilateral optic neuritis, and ten healthy control subjects (HC) were recruited to participate in a pilot study to assess our strategy. Subjects were asked to indicate whether a linearly moving pendulum ball followed a linear 2-D path versus an illusory 3-D elliptical object-motion trajectory, by reporting the ball's approximation to one of nine horizontally-oriented colored wires that were positioned parallel to one another and horizontal to the linear pendulum path. Perceived motion of the bob that moved along wires behind or in front (along the ‘Z' plane) of the middle reference wire indicated an illusory elliptical trajectory of ball motion consistent with the PF. When the neutral density filter titration was applied to the fellow eye the severity of the PF decreased, eventually being fully abolished in all but one patient. The magnitude of neutral density filtering required correlated to the severity of the patient's initial PF magnitude (p < 0.001). We ascertained the magnitude of the visual illusion associated with the PF, and the corresponding magnitude of neutral density filtering necessary to abolish it. •Question: To develop an objective method by which to identify and treat the Pulfrich phenomenon (PF) in MS patients with visual image processing asymmetry from optic neuritis.•Findings: The magnitude of the PF correlates to the degree of neutral density filtering necessary to abolish it (p < 0.001).•Meaning: Characterizing the presence or absence of binocular summation upon low contrast letter acuity testing, has implications for the presence and persistency of the PF.
Visual illusion Neutral density filter Pulfrich phenomenon Asymmetric visual transmission

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