Eyes are getting old and several surgeries, including stints in both eyes to relieve pressure. The pressure went back to normal, but the cataract surgery was a mess.
Back to the topic, on my firearms, most optics and sights are original or close to period correct. Marlins mostly get vintage Weavers and Redfields or original irons. Original 1893 has the original Marbles tang peep. Red dots include a Fast Fire III on a Smith Auto 22 and an Elbit Falcon on an AR... look it up. A couple Springfield 4x14 50's on 308 sniper type stuff and Doctor scopes on what few long distant, flat shooters.
I can still work with all, to some degree but as mentioned above, TALK to your surgeon if you need surgery. My optometrist was phenominal, my ophthalmologist was not successful.
I can see a 4x4 post on a duck blind at 600 yards and a marker buoy at 900 yards clearly with my right (dominant) eye but the front sight is another thing altogether. My left eye is a complete mess, but have an opportunity to see another ophthalmologist in a few months.
Old age sucks, except in fine vintage firearms.
If you can focus on the front sight you are in business...all US military rifles have used peep sights for well over a hundred years. They work.