I shoot with a Gehmann (German) dioapter rear sight. I removed the color filters, as they had a habit of appearing when I adjusted the appeture opening, when I really did not want them to. The diaopter will allow me to see the dust on the lens of the Gehmann adjustable front sight I use! No need for glasses, at least with my good, but older eyes. They are a big help with eye strain, as the time you spend looking through them in a match can be quite a long time, if you are straining to see the front sight. For a couple of years I wondered how the older guys shot so well, untill my friend showed me why.....I use it in a Redfield Palma rear sight, as it is made for metric European inserts, unlike the earlier rear sights they made. They by the rules use a single lens embedded in the rear appeture, with an adjustment ring to adjust focus. Best kept secret at the rifle range, for older eyes.
Hope this helps, Kirk