This is *vital* survival skill for folks who depend on corrective lenses. For example, both my mother and wife are basically blind without their glasses (my mom is actually legally blind without hers); misplaced glasses are a huge problem.
If you are an optometrist, you should teach this to folks first thing when you prescribe lenses for them. It can be an actual life saver, right up their with hands-only CPR and the knowing to Heimlich an infant[*].
If you’re generally curious about pinhole technology and how pinholes work, you can check out this article I wrote for The Magazine, “Light Motif.”
[*] PRO-TIP from a guy that’s done this plenty of times: You lay the kid over your arm and pound her back as though you’re trying to get ketchup out of a bottle. 99.999% of the time, that’ll dislodge the piece of bread or whatever. If you need to do the chest compressions, THEN YOU *SCREAM* AT SOMEONE TO CALL 911 WHILE YOU ARE DOING THEM; that shit is serious. I’ve had to do the Ketchup Bottle plenty of times; it’s scary, but it works like a charm. It’s never gotten to the Chest-Press stage, for which I thank the God Thing Iteration of Your Choosing