Here's my two cents worth….don't worry about keeping both eyes open. I have many new shooters that have issues with keeping both eyes open while maintaining proper sight picture and sight alignment. Use your dominant eye to focus on the front post of the sights, go ahead and close the other eye…remember, the sight picture you should see is the dot or post of the front sight, everything else should be slightly blurry and out of focus.
Concentrate on that front sight, you'll see everything else that you need to see to shoot accurately. Practice without your glasses until you can hit your target, then practice some more with the glasses. Don't set your expectations too high and get frustrated, like everything else in life, practice makes you better. Shoot at close distance to hone your sight picture, breathing, stance, and trigger control. Remember, handguns are not intended to be "long range" tools..concentrate on the accuracy and follow through at short range. When you get comfortable at short range (start at 5 yards, or 15 feet), gradually increase the distance to target. You'll soon find that you can move the target downrange, and still hit it with accurate shots! I really encourage you to seek a NRA certified instructor so he or she can evaluate and correct any problems with your shooting technique.
Best of luck, please contact me if you have any questions.