Visual Electrophysiology in Congenital Nystagmus with Normal Fundus
Thammanoon Surachatkumtonekul MD*, Ngamkae Ruangvaravate MD*, Chuenchanok Sriyakul MD*
Affiliation : * Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To identify the ophthalmic causes of congenital nystagmus with normal eye examination by visual
electrophysiologic tests.
Material and Method: Medical records of patients who presented with nystagmus and no other neurological
sign before 6 months of age with normal eye examination, between February 2004 and February 2005, were
reviewed. Complete ophthalmic examination and visual electrophysiologic tests were performed to identify
the ophthalmic causes of congenital nystagmus.
Results : Thirty-four patients had met the criteria. Leber’s congenital amaurosis was diagnosed in 13 patients
(38.2%) by non-recordable electroretinography (ERG) and normal visual evoked potential (VEP). Idiopathic
infantile nystagmus was diagnosed in 12 patients (35.3%) by normal ERG and VEP. Achromatopsia was
diagnosed in 8 patients (23.5%) by flat retinal cone ERG but normal rod ERG and VEP. Rod-cone dystrophy
was diagnosed in one patient (3%) by abnormal rod and cone ERG.
Conclusion : Visual electrophysiologic study is helpful to identify the ophthalmic causes of congenital
nystagmus. Leber’s congenital amaurosis is a common cause in congenital nystagmus.
Keywords : Congenital nystagmus, Visual electrophysiology, Electroretinogram (ERG), Visual evoked potentials (VEP)
