This report presents two cases of abducens palsy developing with late onset following endovascular treatment for carotid-cavernous fistula. Following this common and effective treatment for carotid-cavernous fistula, an immediate cranial nerve palsy is a common finding. It usually resolves spontaneously. In both these cases, total obliteration of the fistula without a residual shunt was confirmed. However, both cases went on to develop late onset abducens nerve palsy months after the procedure. Both cases went on to require strabismus surgery to treat their ocular motility disorders. The underlying mechanism is unknown and the authors suggest it may be a different mechanism to that of immediate or delayed cranial nerve palsies, due to the fact that the symptoms in these cases did not resolve.