Dear jerryaa,
Will it be possible for you to post some more information about the person with the hemianopia? It is important to know how many weeks or months after the accident, the vision problems started.
I would encourage you to read this article
http://www.uptodate.com/patients/content/topic.do?topicKey=neuro_op/7056#2
It is indeed possible that the helmet may not have been enough to prevent any intra-cranial hemorrhage (bleeding). But we should try to eliminate other possibilities, depending upon the onset of vision problems, age of the person and any investigations done.
Regards
Abhijeet Deshmukh, MD
Hi
Thanks for the post!
Yes, it is possible. Even with the helmet on, if the impact was high, there could be trauma to brain of bleeding inside the skull. However it is also possible in the aura phase of migraine. Brain tumors, hemorrhage in brain, trauma to brain as in this person’s case or diseases like Multiple sclerosis can all cause homonymous hemianopia.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!