Your BP of 140/80 is not bad and does not even need drug treatment but if you have a family history of stroke or heart attacks then your blood cholesterol may be high and needs to be tested & treatment with drugs like Atorovast or other statins. Clopitap tablets or low dose aspirin e.g. 75 mg every night after meal for the rest of your life would be helpful in preventing a similar or other vascular episode in future. Make sure you do not have intolerance to aspirin. This may have caused slight weakness of your eye muscle giving you the double vision.
If you look down the steps with bifocal or varifocals (progressive) glasses that also can give you blurred vision at that distance in which case walk down without the glasses and see.
Treatment with Neurobion tablets or injection is useless and even if it is paresis, it will get better on its own in 1-2 months time.