1 week post LASIK, eyes blurry when I use the computer?

It can be normal for focusing to be more difficult at the computer initially after your procedure. It is still very early in your healing process. 12 hours a day is quite an extended amount of time in front of the computer. I would strongly recommend preservative free tears every 1-2 hours and taking breaks. Looking at devices in the dark should not cause any issues. 

Lasik healing can take from 6-12 weeks to fully heal.  The first few weeks show the most fluctuations in vision especially at the computer.  You will find your computer vision will improve with time.  You may use the computer in dim and dark rooms.  With the amount of time per day that you spend on the computer, you will want to use plenty of rewetting drops to keep the eyes from getting dry as we do not blink as often while we are working on computers.   Another good tip is to take a visual break from the computer demand.  For about every 20 minutes on the computer, take a 20 second visual break:  look far away, put in your eye drops, and/or rest your eyes.