system
Given the following post, respond as if you're commenting on Reddit:
human
Does a fish see clearly when out of the water?

Anytime I open my eyes underwater, everything is blurry, but I can see fine otherwise. Is it the same way for a fish? Can they see fine underwater and then have trouble seeing out of the water? Is there even any way to test this?
gpt
When light moves from one medium to another, it refracts (distorts). The eye evolved underwater, so it evolved to have fluid inside it so light would move from the water into the eye without refraction. Your eyes have adapted to compensate for the refraction that happens when light goes from the air to the fluid inside your eyes. Underwater that refraction doesn't occur so the compensation ends up distorting the image. Fish would have a similar problem out of water. Since they aren't compensating for the refraction, they would also see a distorted image.

Interestingly, since the eye developed underwater it's believed that fish generally have better eyesight than we do, since our eyes are basically underwater eyes that have had to be adjusted (imperfectly) to work on land.