Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
A sudden loss of vision in an eye is rarely due to a pituitary tumor which usually presents a s a progressive
visual field loss. The only probable instance in which a pituitary tumor can cause a sudden visual loss is in case of a pituitary apoplexy which is a sudden
infarction of the blood supply to the gland. Considering his history of
nasal congestion, his sudden
vision loss is most consistent with a diagnosis of
optic neuritis which is common in the presence of sinusitis or dental infections. Also since the clinical exam did not pick out any swelling of the
optic nerve or macula, it is most consistent with the
retrobulbar neuritis variant. He will need a baseline blood workup such as CBC, blood sugar and lipid levels, ESR, VDRL, Mantoux and any other blood investigations to rule out infectious diseases endemic to your area. Also a brain MRI is indicated in these cases to rule out demyelinating plaques. Treatment involves a brief course of steroids which hastens the recovery.
Hope I have answered your query.
Let me know if I can assist you further.