Delayed visual disturbances in carbon monoxide poisoning: Identification and evaluation.

INTRODUCTION Carbon monoxide (CO) poisoning may result in neurological and neuropsychological sequelae, including visual problems. We performed neuro-optometric evaluation on patients who reported vision or attention complaints after CO poisoning. METHODS We performed a retrospective chart review of patients with continued symptoms after CO poisoning who had neuro-optometry evaluations between 8/18/2009 and 8/31/2013. Data collected include general demographics, symptomatic changes prompting neuro-optometric evaluation and pathologic findings during examination. RESULTS We identified 43 CO-poisoned patients receiving neuro-optometry evaluation (17 male (40%), 26 female (60%)). The patients' mean age was 41 ± 14 years (range 17-72 years), and 28 (65%) had CO exposure durations > 24 hours. Neuro-optometry evaluations were conducted at 2.4 ± 1.7 years from poisoning (0.05-7.1). Of 37 patients reporting onset of visual symptoms, 34 reported symptom onset within six months of poisoning. Thirty-nine patients (91%) demonstrated visual pathology attributable to CO poisoning. Peripheral vision defects were detected in nine individuals (21%), while central vision defects were noted in only two (5%). Other present findings were: convergence insufficiency 28 patients (65%); oculomotor defects 14 (33%); accommodative dysfunction 10 (23%); divergence insufficiency six (14%), and convergence excess two (5%). Clinical dry eye was present in four (9%). Eleven patients (26%) received visual evoked potential (VEP) testing; eight (73%) were abnormal. CONCLUSIONS These findings support that CO poisoning can result in visual pathology. Of clinical importance, some of these abnormalities may be responsive to rehabilitative interventions. Specialized visual evaluation and testing should be an integral aspect of care in CO-poisoned patients with visual complaints or exam findings.