Visual Disorientation

Visual Disorientation

Visual disorientation refers to the inability to perceive more than a fragment of the visual field at any one time; it is sometimes characterized as a shifting fragment or island of clear vision. There may be difficulty fixating static visual stimuli and impaired visual pursuit eye movements.
Visual disorientation may be demonstrated by sitting directly opposite the patient and asking them, while looking at the bridge of the examiner’s nose, to reach for the examiner’s hand held up in the peripheral field of vision. Once contact is made with the hand, the examiner holds up the other hand in a different part of the field of vision. Individuals with visual disorientation will find it hard to see the hand and will grope for it, sometimes mistakenly grasping the examiner’s clothing ("tie sign") or face.
Visual disorientation is secondary to, and an inevitable consequence of, the attentional disorder of dorsal simultanagnosia (q.v.), in which the inability to attend two separate loci leads to impaired localization. It may be a feature of Alzheimer’s disease; indeed, sometimes it may be the presenting feature, but there are usually signs of more generalized cognitive problems (e.g., impairment of episodic memory).

References

Farah MJ. Visual agnosia: disorders of object recognition and what theytell us about normal vision. Cambridge: MIT Press, 1995

Cross References

Simultanagnosia; Visual agnosia