Retinography and visual evoked potentials in differential diagnosis of congenital nystagmus

Congenital nystagmus is the most common form of nystagmus in children. It occurs in the fi rst three months of life. It can be sensory, caused by damage to the fi eld of retina or optic nerve, neurologic, or idiopathic. Simultaneous electroretinography and visual evoked potentials are noninvasive electrophysiological techniques that make it possible to identify the possible cause of congenital nystagmus. The aim is to show the role of simultaneous electroretinography and visual evoked potentials tests in diff erential diagnosis of nystagmus in a 7-year-old female with ocular albinism. The patient was referred by an ophthalmologist to electroretinography and visual evoked potentials for strabismus and nystagmus before deciding on surgical treatment. Testing is performed with the patient awake; electroretinography response is recorded by skin electrodes placed below the lower eyelid, and visual evoked potentials above the primary visual cortex. Stimulation is performed by Grass photo stimulator with white, red and blue light for the electroretinography and visual evoked potentials fl ash, as well as the structural stimulus. Flash electroretinography was normal, but the fl ash visual evoked potentials and visual evoked potentials structured onset indicated contralateral asymmetry. The amplitude was signifi cantly greater above the contralateral hemisphere, and interocular diff erences indicated inverse polarity. This cross asymmetry is present in albinism. The clinical somatic status of the skin and skin derivatives was normal. Magnetic resonance imaging of the brain was also normal. The patient is probably a case of isolated, ocular albinism. In conclusion, simultaneous testing by electroretinography and visual evoked potentials allows for diff erentiation between sensory (retinal or postretinal), neurologic and congenital idiopathic nystagmus. The nystagmus in this patient was caused by ocular albinism.

Read more