Ocular motility anomalies in developmental misdirection of the optic chiasm.

Abstract

A 35-year-old normally pigmented man underwent monocular hemifield visual-evoked potential examinations that indicated a lack of normal decussation of nasal paramacular retinogeniculate fibers in the optic chiasm. We studied effects of this anomaly on ocular motility using electro-oculography and the magnetic search-coil technique. The patient exhibited horizontal congenital nystagmus with a predominantly positive exponential waveform. Horizontal smooth pursuit and optokinetic nystagmus were consistently reversed, independent of eye position in the orbit. Vertical tracking was uniformly normal. Horizontal vestibulo-ocular reflexes recorded in the dark during passive rotation exhibited normal gain and phase, whereas rotation recorded in the light reduced gain. Although active head movements reversed horizontal vestibulo-ocular reflexes, vertical vestibulo-ocular reflexes in light and darkness were normal. Our study suggested an association between a lack of normal decussation of retinal fibers in the optic chiasm, and reversed visual tracking and congenital nystagmus.

• Authors: J W McCarty, J L Demer, L A Hovis, M R Nuwer
• Journal: American journal of ophthalmology (Am J Ophthalmol) Vol. 113 Issue 1 Pg. 86-95 (Jan 15 1992) ISSN: 0002-9394 [Print] United States
• PMID: 1728153 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Topics

• Adult
• Electrooculography
• Evoked Potentials, Visual
• Humans
• Magnetic Resonance Imaging
• Male
• Neural Pathways (abnormalities)
• Nystagmus, Pathologic (congenital, physiopathology)
• Optic Chiasm (abnormalities, physiopathology)
• Optic Nerve (abnormalities, physiopathology)
• Saccades