Why are my eyelids blue after an upper blepharoplasty 9 days ago? (photo)

It is not uncommon for the lower part of the eyelid to be slightly discolored for a week or two following upper eyelid blepharoplasty.  This is likely due to a small amount of residual blood/bruise under the thin eyelid skin along with alternations in the eyelid vasculature.  This will improve with time.  

This discoloration tends to improve with time.  You are very early from your surgery, so you really need to give yourself time to heal.  What is amazing is how rapidly things can improve.  I would recommend patience here.

Skin discoloration after blepharoplasty

In the first few weeks after a blepharoplasty the skin color of upper lids
can appear different than normal. This is due to some bruising, vascular
changes, etc. All that will settle down and look normal within few weeks. In
your particular case you look great after 9 days post blepharoplasty.

You are just entering the second phase of healing, though late. Thus on average your healing should be a week you will take a month to obtain full healing... 

It is not uncommon to have a change in the coloration of the eyelids this soon after surgery.  You have resolving bruising and changes in vascularity at this point.  This coloration will continue to improve with time.