How fragile are dissolving stitches for an under blepharoplasty?

The skin sutures should all be out at this point.  If there are any visible, you need to immediately bring this to the attention of your surgeon.  This is a surgery that does not require permanent sutures.  Smiling should be just  not be a problem.  Please contact your surgeon and discuss your concerns with them.

Unless you purposely try to disturb the sutures, there shouldn't be a problem with dissolvable sutures. It's best to see your doctor about any residual sutures still present at this point.

It will take a few weeks for the incisions to heal well. Unless you pull hard on your lower lid, the incisions should not open after 10 days.

Congratulations on your lower blepharoplasty! At 10 days, I would say that you are good and that you can breathe a sigh of relief. Every surgeon has a different technique. For skin incision lower blepharoplasty, I close with 6-0 plain fast absorbing plain gut, which loses its strength in about 5-6 days anyway. If you had a transconjunctival blepharoplasty (from the inside) so surgeons do not close that incision w/ sutures at all and leave it to heal on its own. Best always to ease your mind by asking your surgeon directly. 

Dear monimoo, Unless you pull down on the eye you are fine. Just use gentle care while washing your face and applying eye cream. If you have any concerns your surgeon can show you the appropriate pressure to use. Best regards, Michael V. Elam, M.D.

since there should be minimal tension on the lower eyelid skin, assuming conservative horizontal skin excision before closure, normal eyelid opening and closure should not present any problem.  a hematoma could force open the incision but I have never seen that happen.  I personally use rapidly absorbing catgut sutures for the lower eyelid closure because the eyelashes and non absorbing skin closure sutures such as prolene get tangled up making removal awkward at best.