Since the basic rule of pistol shooting is KEEP THE FRONT SIGHT IN FOCUS, and since you can't focus clearly on the sights AND the target, I suggest holding off on changing the sights on your 686.
I suggest a set of glasses with the proper diopter lens in your shooting eye.
Here is my set of Knobloch glasses. I have done a lot of bullseye shooting over the past 50 years, and ,my eyes have changed a lot during that time. The replaceable lens allowed me to keep that front sight in FOCUS. You can click on the pic to expand it.
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The glasses have an adjustable diaphragm behind the lens, which will help the target focus, the glasses are focused on the front sight. The thing on the left is an temporary aperture to insure the lens is aligned properly with your eye, the sights and the target.
I would take my guns to the optician's office and hold them up and he would hold a lens in front of my eye, and I would choose the lens which made the front sight clearly in focus. I had three lengths of guns, a S&W Model 52 or 1911 length, a 7 3/8 barreled Model 41, and a Hammerli Free Pistol which was quite long. I had a lens for each. The round lenses were not very expensive, I don't remember the cost.
Later I made this "Fake Gun" to use instead of hauling my guns to the office. It was a stick , with a handle, and three 1/4 square pieces of keyway material at the front sight distances. I could always add a new "front sight key" at a different distance.
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Over the years I had a lot of lenses as my vision got worse.
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After I got my cataracts removed, I had to get new lenses.
I don't believe any colored sights will help you, which is why I suggested you not change your 686. I believe the solution is in lenses, not in sight modification.
The other suggestion of a "Red Dot" sight is also viable. I did not do this because a) back 50 years ago there were no red dot sights, and b) I like iron sights.
I hope it all works out for you.