A bridge piercing, also called an Erl, is a horizontal bar across the bridge of the nose. It's considered a surface piercing, since most people don't have a lot of flesh for the jewelry to grab onto in this area, so the risk of migration and rejection is high.
The best jewelry for a bridge piercing is a small curved barbell. A straight barbell will cause too much tension on the edges of the fistula and could increase the chance of migration.
Contrary to the rumor that a bridge piercing will make you cross-eyed, no Erl piercees have reported any involuntary eye-crossing. In fact, most forget it's even there. If you're noticing the jewelry out of the corner of your eye, the bar is probably too long. It shouldn't be any more visible to you than your nose itself.
It also doesn't interfere with the wearing of glasses or sunglasses. Just make sure it's pierced up high enough and you should be fine.
The starting gauge of your piercing needs to be determined by your piercer, based on how much tissue you have available in this area. The larger gauge you can comfortably wear, the better (to hopefully prevent rejection).
It's important to keep the area free of exposure to harsh cleansers, makeup, and hair products during the initial healing time, which will take about 8-12 weeks. At that time, you can change to a shorter curved barbell if needed, but it will take an additional period of several weeks for the inner tissue to heal.