The Pulfrich phenomenon and its alleviation with a neutral density filter.
A case is described in which a presumed vascular accident resulted in long-standing visual difficulties in both reading and the analysis of vectors of moving objects. Clinical examination revealed minimal right optic atrophy with a relative superior altitudinal visual field defect associated with a positive Pulfrich effect. A partial head turn to the right in association with paresis of saccades and pursuit eye movements to the right was also evident. Spectacles for distance which incorporated a neutral density filter before the left eye were prescribed. These practically eliminated the Pulfrich effect and alleviated the problems of vector analysis. A near correction was provided which incorporated prisms with bases to the right. This eliminated the reading difficulties. The visual problems experienced by patients suffering from a positive Pulfrich effect are described and discussed.
Heron
G
G
Department of Ophthalmic Optics, Glasgow College of Technology.
Dutton
G N
GN
D005139:Eyeglasses; D005260:Female; D006801:Humans; D007088:Illusions; D008875:Middle Aged; D009039:Motion Perception