If you wear glasses that invert the image, your eyes will adapt to the image after a few days. There is some information on the Wikipedia page of the guy who discovered it (https://en.wikipedia.org/wiki/George_M._Stratton).
I guess it was because the muscle adjustments resulted in my eyeballs getting rotated.
It all proves how we don't directly see what's coming thru our eyes - we see the mental model that our brain maintains about the outside word, built/updated via what's coming in thru our eyes.
Another question I had is could you learn to instantly switch between them? If you alternated between wearing the glasses and not every few days, would the adaptation period shorten each time? Would it eventually become instant? This is usually the case for motor skills e.g. controlling something with an inverted vs. non-inverted axis.
You can also have glaucoma or other 'typical' diseases of the eye. Things like blindspots from welding or lasers.
The visual system in healthy people is already a bit odd. You have the foveal blindspot, the differing distribution of rods and cones, the unseeing neurons that do light sensation for melanin production, etc.
Really, the whole sensory chain is one giant bag of 'wait, it does that? huh?'