This is something that I naturally started doing after practicing shooting both eyes open. I see a lot of people shoot with one eye and concentrate on aiming, same as if they were shooting a deer or in an accuracy contest. IMO in a self defense situation you will want both eyes open and on the target so you can continually assess the threat and your surroundings. Concentrating on the sights will take too long and cause you to lose focus on the attacker.

I have found this technique is a lot easier with the tritium sites on my glock as they are easier to decipher when blurry. The target sights on my 686 also work well, but the fixed sights on my sp101 do not work very well as they blend into the gun