I read your query and I understand your concern. It would have been useful to know also whether he had contrast exam during MRI. Enlargement of the pituitary gland can have many different causes, some are common and some are rare. The overwhelming part, including most common ones (benign tumors of the pituitary gland) are slowly progressive conditions which in my opinion can wait until next week. I am not even sure that it s the cause of the symptoms you mention, it is more probably finding caught by coincidence (compression of the optic chiasm can cause vision field issues, but not double vision - it doesn t look to compress the chiasm anyway). So unless there are new signs and quick deterioration of his condition I don t think you should rush to the ER. I hope to have been of help.