I'm right handed and have a left dominant eye.

Years ago I got used to shooting handguns with both eyes open using the left eye. I shoot long guns off the right shoulder using the right eye. I can close each eye independently, which is a struggle for some folks.

Back in 2010 I had cataract surgery. My vision is now 20/40 uncorrected (though I almost always wear glasses anyways). The right eye is set up for close range and the left/dominant eye is set up for distance.

I have had increasing difficulty getting a clear sight picture with a handgun using the left eye, particularly when shooting in indoor ranges with shadowy light.

Recently I have begun to retrain myself to shoot handguns using the right eye, although I cannot yet shoot with both eyes open.

Getting old is a continual process of making adjustments . . . .