shycat,

Thanks for your posted question.  I have never seen, or read a report that high blood pressure causes darkening of the area around the eyes.  Also, none of the usual medications used for high blood pressure cause this problem.  Some older medications used for some psychiatric disorders have been known to cause this problem.  And of course, I've seen some patients who have developed this situation with no reason ever found.  Patients often blame it on fatigue or stress, but again, no medical basis. 

I would ask your doctor for his opinion about possible causes.  Also consider the opinion of a dermatologist.  There are some skin creams that can lighten areas of deep pigmentation, so this might be an option. 

I hope this has been helpful.

Martin Cane, M.D.