Caloric Tests in Blind Patients: Electronystagmographic Study

Abstract

IT IS WELL ESTABLISHED that ocular fixation inhibits caloric nystagmus; when the ocular fixation is abolished during a caloric testing the frequency of the nystagmus diminishes and the amplitude increases.¹ The question of how caloric nystagmus in blind subjects compares with that of a normal population has been given contradictory answers. There are few references on this specific subject. Jones² wrote that caloric nystagmus is greater in blind patients, whereas Dylewski³ found diminished responses to both caloric and rotatory stimulations coincidentally with the loss of vision. Scott⁴ reported that although labyrinthine stimulations produce normal nystagmus in the blind, the slow phase of the nystagmus is not constant and the eyes roll aimlessly about. Walsh⁵ also reported that in patients with intracranial tumors and papilledema the caloric nystagmus was not altered by lowered visual acuity or even by blindness. In fact the nystagmus was even present