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Published on: April 25, 2011
Carbon monoxide poisoning causes optic neuropathy
1Ophthalmology Department, St James' University Hospital, Leeds, UK.
Purpose:
To describe the electrophysiological and psychophysical effects of carbon monoxide (CO) poisoning on visual function.
Methods:
Three patients are presented who suffered CO poisoning, two due to suicide attempts and one in the course of a road traffic accident. After a full ocular examination, Goldmann visual fields, flash and pattern visual evoked potentials (VEPs) and flash and pattern electroretinograms (ERGs) were tested.
Results:
Electrophysiology showed reduced or absent N95 components of the pattern ERG and delayed, reduced VEPs. A positive-negative-positive (PNP) VEP waveform was seen in two cases. In one case, where presentation occurred at an early stage, visual and electrophysiological function was improved with hydroxycobalamine.
Conclusions:
The combination of ERG and VEP findings suggest that CO poisoning can cause a toxic optic neuropathy that may have a similar aetiological mechanism to that in tobacco amblyopia. Early treatment with hydroxycobalamine may be of some benefit.
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