Can I correct large scar under my eye 6 months after lower blepharoplasty? (Photo)

I have never really been impressed with the "help" from CO2 laser resurfacing for an issue like this.  Your lower bleph scar is not well designed and deviated from the lashes. It should more closely hug the lash base. To improve this, the scar needs to be lifted to this level. You have waited sufficiently. The challenge is that you need to find a surgeon who is comfortable and experienced with this work.

Even in the best executed eyelid surgery skin incisions can scar.  I understand that you are self conscious with the appearance of your scar but I suspect like all things, we tend to focus on the things that bother us.  In your particular situation, if silicone gel products on the wound do not help the scar mature then a revision of the scar with excision would likely be necessary and can be performed under local anesthesia with very little recovery.

You have  some options to try and improve the scar.  One is to excise the scar.  The issue here will be how much laxity there is in the area.  If the skin is quite tight, it may not heal well the second time and you will get a new scar.  The other option is to do some laser resurfacing.  This can help to flatten and soften a scar.  May need a few treatments, but the results can be quite good.  

From looking at your photos I think your surgeon could do a very limited excision of that scar and put in a few sutures.

You have several options for this scar. You may find that it improves somewhat with time (up to 12 months. CO2 fractional ablative laser is a non-invasive option to induce/ revise collagen and flatten the scar. You could proceed with CO2 laser treatments now, and after another 6 months (possibly several treatments) decide whether you need to have surgical revision. In my practice I see patients for scarring after various procedures and they have been pleased with the CO2 laser scar treatment. Best wishes with your decision.