Accommodation power determined with visual evoked cortical potentials in psychogenic visual disturbances

Abstract

Accommodation power was measured with pattern visual evoked potentials in 12 normal subjects and three patients suffering from psychogenic visual disturbances and accommodation failure. Steady-state visual evoked cortical potentials recorded by increasing a minus-power lens in front of the eye in 1 diopter steps. The regression line was established from the visual evoked cortical potential amplitudes vs accommodation stimulus plot, and the objective accommodation power was determined by extrapolating the line to zero amplitude. The accommodation power measured by visual evoked cortical potentials was larger by approximately 2 diopters than that obtained subjectively by near-point rule in normal subjects. The subjective accommodation power was remarkably low for their age in each patient but the objective power was normal. These results suggest that the decrease of accommodation in these patients was caused by psychogenic mechanisms, and visual evoked cortical potential measurements of accommodation could provide helpful information for diagnosis.

Colour Vision Disorder due to Conversion Disorders in Childhood

“…Die häufigsten Symptome sind variabel ausgeprägte Visusminderungenein-oder beidseitsund Gesichtsfelddefekte. Auch Diplopie mit Akkommodationsstörungen[19], Pseudoparesen, Blinzeltics, willkürlich induzierter Nystagmus, Ptosis oder Trichotillomanie sind beschrieben[1, 8, 20 -22]. Isolierte Farbsinnstörungen, wie in unserem Fall, sind jedoch ausgesprochen selten.Zahlreiche Untersuchungen und Bedeutung der schnellen DiagnosestellungPsychogene Sehstörungen stellen im Praxisalltag häufig eine Herausforderung dar.…”

Standardized visual evoked potentials for telematic electrodiagnosis from five laboratories in three European countries

“…However, thereisalsoconsiderable variabilitybetweenlaboratories inthenormal values of the latency and amplitude of PR VEPs. This variability is partlydue todifferences betweenindividuals but it is also the result of the recording methodology used, including the stimulus luminance 8 , contrast 9 , colour 10 , spatial 11,12 andtemporal 6,13 frequencies, locationof the stimulus pattern 14 , accommodation and blinking [15][16][17] , filter setting and stability over time of the stimulating devices andthe amplifiers 18 . All these variables needto be kept withinnarrowlimits toensure the reliabilityof the results, since uncontrolled change in any one of themaffects the interpretation of the test.…”