Daryl's sights are just what I use with a couple of modifications. The bead should fit the notch as Daryl said,with little or no light on either side, and should be a different color, so you can distinguish it from the rear sight. If you need light on either side of the sight, your eyes aren't truly bad, because that light would look like a supernova on top of your barrel, if they were. Thinning the center of the rear sight, and filing angles to reduce reflected light, and create shade for the rear sight are important. The long gradual V that culminates in the round bottomed notch is very important. It forces the eye to focus on the notch.
I take it one step farther. I often bore the center out of the rear sight, and replace it with a thin sheet of sterling silver. I then file my gradual V, and round bottom notch in it. This insures the rear sight will always be a deep flat black ( after the first few shots) because the powder residue from the pan will tarnish the silver very black. A piece of refrigerator magnet material stuck to the rear sight base will allow you to place the rear sight where it will work best for your eyes.
Hungry Horse