It’s still water isn’t it? Shouldn’t it have the same effect
In: 4
The liquid around, just like your tears, is not pure water. It has some salt (or other components) in it.
The key concept is “osmosis”. For some membranes (like some cell walls), water tries to have the same concentration of stuff in it (like sugar, salt) on both side of the membrane.
Otherwise, water from the less salted side will move to the more salted side. If a lot of water goes inside the cell or leave the cell, it’s bad for it. That’s why salt kills slugs (and hurts on a wound).
For your eyes, pure water will hurt, and water with too much salt (sea water for example) will hurt as well. But just the good amount will not hurt, and that’s typically what you’ll have in eye drops.
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