Turning eyelids inside out
I think I was about 7 years old when I first saw someone turn their eyelids inside-out. It was the sort of thing you just never think of trying until you see it happen, and realise that people’s eyelids don’t tear, or their eyeballs fall out as a result.
Lid eversion (it’s proper name) is now something I do to people many times a week as part of examining eyes – looking for embedded foreign bodies, checking for signs of infection or allergy, or in the search of a lost contact lens…
Turning your lids inside out is possible because the main ’substance’ of the upper lid is a collagen plate that isn’t firmly attached at the top to your eye socket (it has to be this way, otherwise your lids would get in the way of your vision when you look up…). Once you evert a lid, the plate adopts a different position; it can stay quite stably inside out if you want it to.
Some people have an unfortunate condition called floppy eyelid syndrome, often going along with sleep apnoea, where their eyelids will evert by themselves. If that happens during sleep, the eye surface can get quite dried out overnight leading to sore, red eyes the next day.
