I have a Merit adjustable aperture that uses a suction cup mount to eyeglasses. Positioning it for using open iron sights on a rifle, and adjusting the aperture size, it makes both sights and target clear. I bought it for pistol shooting, but it also works well for iron sighted rifles. The image is dimmer, so it won't work well for hunting in the woods, but is great for range shooting.
You can take black target pasters or electrical tape and punch holes of various sizes to find the right size for the condition and stick them on your glasses where you normally look when shooting. I did that and won an inter-club military open-sight benchrest match at 100 yards, using a borrowed Swede 6.5 and paper-patched cast bullets. The 5-shot group was about 1 1/4", as I recall.