Question about vision through varifocal lenses

[LookingThroughGlass]

Hello! I wondered if anyone knowledgeable could answer this question. Not at all important, I am just curious.

I wear varifocals. Whenever I get a new prescription, for a while, any screens appear to be narrower at one end than the other, as if the vertical axis at one side is shorter than the other. Then it seems something adjusts and it doesn't happen any more.

If I revert temporarily to my old pair (e.g. if I'm dyeing my hair, to avoid damaging the new ones) I get the effect again, with the old glasses.

My question is, what is adjusting or compensating for this effect over time? Is it my brain or my eyes?

Any info gratefully received!

Your eyes are just devices to channel focussed light onto your optic nerve. Your brain is what interprets the signal. Most likely your new glasses are sending a slightly different light signal which your brain has to learn how to reinterpret. Your brain may send a message to the ciliary muscles to slightly adjust your lens shape, but it's amazing how quickly the brain adapts to new information.
Your brain now knows how to process and interpret image data from both sets of glasses and is switching between the two learned methods when you change glasses.

Thank you @CurlyKoalie - that's really interesting. The brain is so fascinating!