I was having a random conversation about why our eyes get blurry sometimes - and other times they are not. Also why glasses make things sharper? Is the blurriness caused by the eyes themselves or by the mind/brain? After discussing it for quite a while I realized something that I hadn't before - that our eyes are separate organs that are really only connected by some blood vessels and the optic nerve. That the blurriness must be caused by the eyes being tired in the same way that other separate (but connected) organs are. The longer you use them - the more worn out they become and need to rest to recover.
I also considered what it would be like if you had an "eye transplant" and that all eyes are not necessarily the same. What if you had your eyes replaced with someone else who had better vision? What if some eyes are more or less evolved and everyone see's things differently?
The conversation soon turned to glaucoma - but we didn't really know what glaucoma was! I decided to google it and coincidentally - but not surprisingly Leonardo da Vinci came up in the results. I had already known of his advancements in optics and vision but was interested in what I found:
"Leonardo Da Vinci is frequently credited with introducing the idea of contact lenses in his 1508 Codex of the eye, Manual D, where he described a method of directly altering corneal power by submerging the eye in a bowl of water. Leonardo, however, did not suggest his idea be used for correcting vision—he was more interested in learning about the mechanisms of accommodation of the eye."This is yet another example of one of his ideas/inventions that, while correct, wouldn't have been able to be made. They weren't capable of making contact lenses 500 years ago.