A 54 year old Chinese man who presented with complaints of binocular horizontal distance diplopia, more on side gazes to both directions. He details that the images are sometimes close together but sometimes they are far apart. The diplopia is only periodic and worsens when he is concentrating hard or tired like after a long drive. He does not have other symptoms suggestive of amaurosis fugax.
He had an epidermoid nasopharyngeal cancer about eighteen years ago in 1985 that was irradiated with resulting necrosis of brainstem and lower cranial nerves. Staging work-up revealed this to be Stage I disease, Ho’s classification. He was treated with a radical course of radiotherapy from November 4, 1985 to December 14, 1985. 5950 rads were delivered to the nasopharynx and 4550 rads prophylactically to the neck. Post-radiotherapy nasopharyngeal biopsies have all been negative. He is otherwise healthy.
He is not on any regular medications. He is a non-smoker but a social drinker with about 5 drinks a month. Except for liver cancer in his mother who died at 63 years old, there is no other history of cancer or ocular diseases in the family. His four siblings are alive and well. He came to Canada in 1988 and had no recent travel history.