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Eye color can change
Neither blue nor green pigments are ever present in the human iris or ocular fluid. Eye color is therefore something like the sky, it depends on the lighting conditions, especially for lighter-colored eyes.
If your eyes are blue, you share a common ancestor with every other blue-eyed individual in the world
The very first person to ever have blue eyes lived around 6,000 to 10,000 years ago. Back then, everyone had brown eyes.
Each eye contains 107 million cells and all are light sensitive
Seven million “cones” helps you see color and detail while the 100 million “rods” help you distinguish black and white. So, less than a tenth of your visual receptors actually detect color.
20/20 vision = normal vision
This number is largely arbitrary but eye doctors determined that people ought to be able to read a chart from 20 feet away. This is normal vision under normal lighting conditions.
If you wear glasses that flip images upside down, your brain corrects your vision
Even though you’d see things upside down, your brain will eventually adapt and you will begin to function as though you are seeing things right side up (even though you’re really not). There have been several experiments done on this.