Functional neuro-ophthalmology

Patients with physical signs and symptoms for which no adequate organic cause can be found may receive any one of a large range of diagnostic labels, including functional illness, functional overlay, hysteria, hysterical overlay, conversion reaction, psychophysiological reaction, somatization reaction, hypochondriasis, invalid reaction, neurasthenia, psychogenic reaction, psychosomatic illness, malingering, and Münchausen syndrome. In this chapter, we describe both common and uncommon "functional" ocular symptoms and signs, including visual loss in one or both eyes, constricted visual fields and other field defects, various types of ocular motor dysfunction, including disorders of ocular motility and alignment, disorders of pupillary size and reactivity, and abnormalities of eyelid position and function. We also discuss and illustrate the methods by which the nonorganic nature of these manifestations can be determined. In many cases simple techniques performed in the clinic are sufficient to establish a diagnosis of nonorganic ocular disease, whereas in other cases ancillary studies such as electrophysiological testing may be necessary. The chapter also describes the appropriate approach that the physician should take when dealing with a patient who has proven functional ocular signs and symptoms.