When a small target is oscillated in front of a patient with binocular vision, patient sees movement of the object in elliptical orbit rather than to and fro path. What is this phenomena known as?
Ans: (b) Pulfrich phenomenonRef: Albert and Jacobie's Principles and Practice of Ophthalmology, 3rd edition, Page 3874Oppenheim Phenomenon:The great toe dorsiflex when the periostium of the tibia is rubbed with the knuckles.Other three options are seen in multiple sclerosis.Uthoff's Phenomenon:Seen in multiple sclerosis.Worsening of neurologic symptoms.Transient visual blurring during exercise, during a hot bath or shower, or during emotional stress. Pulfrich Phenomenon:Seen in:Multiple sclerosis,Cataract,Optic neuritis.Because optic nerve damage delays transmission of impulses to the visual cortex, patients with unilateral or markedly asymmetric optic neuritis may experience the Pulfrich effect or stereoillusion.The examiner oscillates a small target in the frontal plane while the patient binocularly observes it. The delay in signal transmission from one eye to the visual cortex creates the illusion that the target appears to move in an elliptical rather than a to-and-fro path.This disparity in time, caused by the difference in latency between eyes, is interpreted as a disparity in space that results in the stereoillusion.Paroxysmal Convergence Spasm:Rare but typical symptom in multiple sclerosis due to abnormal excitation (In MS, not only delay in conduction occurs, sometimes spontaneous excitation occurs).Due to demyelination plaque in medial longitudinal fasciculus.
Oppenheim phenomenon
Pulfrich phenomenon
Uthoff phenomenon
Paroxysmal convergence spasm phenomenon
Examination of the Eye