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Optic Neuropathies Associated With Multiple Sclerosis (MS) and Neuromyelitis Optica Spectrum Disorders (NMO-SD)
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Another phenomenon experienced by patients of ON is Pulfrich phenomenon, which is the abnormal perception of movement in depth (14). The Pulfrich effect is due to a delay in neural conduction along the optic nerve and can be simulated in normal vision by placing a neutral density filter (dark glass) in front of one eye.
Visual systems
Published in Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol, Handbook of Aviation and Space Medicine, 2019
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol
‘Pulfrich effect’: optical illusion where an object moving in parallel plane appears to approach and/or recede from viewer if there is significant luminance difference between the eyes: Visual latency is shorter for brighter image.Difference in processing times between eyes causes depth effect.
Non-surgical treatment options for presbyopia
Published in Expert Review of Ophthalmology, 2018
Nonoptical methods of treatment as yet remain controversial or unproven. Use of pharmaceutical agents to produce monocular or binocular pupillary miosis [33] and, through the resultant increased ocular depth-of-focus, improve near vision, is fundamentally unattractive as it reduces retinal illuminance in eyes, which already have lower transmittance than in the young. Hence, there are obvious adverse impacts on mesopic and scotopic vision. In the monocular case where the retinal illuminance in each eye differs, the Pulfrich effect may occur, leading to false judgments of the trajectory of moving objects and possible hazard [123]. The use of lipoic acid-based products to reduce the rigidity of the crystalline lens [40] is as yet unproven and may not be free of unwanted side effects.
The Pulfrich Phenomenon: Practical Implications of the Assessment of Cases and Effectiveness of Treatment
Published in Neuro-Ophthalmology, 2018
Jane Farr, Emily McGarva, Jenny Nij Bijvank, Hans van Vliet, Hinke Marijke Jellema, Michael D. Crossland, Axel Petzold
A crucial factor in visualising the provoked Pulfrich phenomenon is the structure of the background to the object. The viewer’s eye movements track the motion of the pendulum and this movement in conjunction with the viewer simultaneously observing a stable background results in this displacement. The background requires features enabling the exploitation of disparity in order to achieve the illusion of depth and for the Pulfrich effect to be optimally demonstrated.9