I saw a commercial for Vuity eye drops. They claim these eye drops can actually improve your vision at close range. A quick check of the claim seems to add up. https://www.today.com/health/health/vuity-eyedrops-fda-approved-replace-reading-glasses-rcna10140 https://www.webmd.com/drugs/2/drug-182672/vuity-ophthalmic-eye/details Clever! This works on the same principle as a pinhole camera. You can do the same thing using a sheet of paper with a pin hole in it. You can also curl your fingers to form a pin hole and look through that. The key is that by reducing the aperture size [what ever you are looking through] to a small hole, light rays that are divergent wont make it through. Only light rays that are parallel to the line of sight will make it. By reducing the size of your pupil you do the same thing. You make a pinhole. This acts as a focusing lens for people with poor vision at close range. Curling your fingers to make a pin hole and looking through that, was a trick and old physics professor of mine taught us. He ran every day but left his glasses in his locker when he ran. He would use the pinhole trick so he could read the numbers on the lock to unlock his locker, when finished with his run.
A pinhole camera is a simple camera without a lens but with a tiny aperture (the so-called pinhole)—effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box, which is known as the camera obscura effect. The size of the images depends on the distance between the object and the pinhole... https://en.wikipedia.org/wiki/Pinhole_camera
This may explain something I've noticed since my eyesight at close range started to decline. If I can't read something because the print is too small, by shining a light on the print, it is easier to read; that is, I noticed that at times the print seemed to be more in focus when lit. Of course I assumed it was just easier to read because it was brighter. But by shining a light on the print, my pupil likely contracted in response, which according to the reasoning above, would make the print more focused. So good or even bright light on the object of interest may literally make your eyesight better.
Another way to do the same thing is to make a small hole using your finger and looking though the small hole. This is good if you want to read a price tag and your poor eyes prevent this.
Using eye drops versus wearing glasses? Arguably wearing glasses is less invasive. But this case is unique in that this chemical has been used in stronger doses to treat glaucoma, for over a century. So it is extremely well tested and proven to be safe; esp given that the dosage is very low compared to the historical use.
One of the things I was taught regarding wilderness survival is that makeshift glasses can be made by poking many tiny holes in a strip of paper, opaque plastic bag or preferably duct tape. And it does work to improve vision accuracy to a degree, but at a substantial loss to peripheral vision, obviously.
