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This article originally appeared in Issue 6 of our magazine.
Warning! This article is meant to be a quick overview and not a detailed guide on improvised visual improvement methods. Whenever possible, always carry spare prescription glasses or contact lenses. Attempting to see without prescription eyewear is solely at the reader’s risk.
A bespectacled man, who only longs to read, survives a nuclear holocaust and finds himself the last man on Earth at a library full of books. He thinks he finally has all the time in the world to pursue his favorite pastime…until he breaks his only pair of glasses. This ironic tale was the plot of “Time Enough at Last,” a 1959 episode of The Twilight Zone. Although this man’s misery played out in a sci-fi TV show, his predicament is something that anyone who has corrective lenses can relate to and should be aware of.
In any type of emergency, there is a risk losing, breaking, or not having enough time to don your glasses. Contact lenses require even more time to put on, can take more care to maintain, and are nearly impossible to reuse or find if lost. But what if a disaster hits unexpectedly? What do you do if you are caught without the benefit of having your optical aids?
Fortunately, there is a way you can focus your blurry vision quickly and without any tools — in fact, all you need is your hand. File this impromptu sight-restoring maneuver in your mental survival skills toolbox under “just in case.”
By forming a small “pinhole” with your fingers and looking through them, you’ll find your vision is significantly sharpened, even if you regularly have very blurry vision. Go ahead, take your glasses off, and try it. Neat little trick isn’t it? This simple action can help you when you’re in a pinch. But just how does it work?
Vision is our brain making sense of light that is collected by our eyes. As light bounces off an object, it travels into our eye, focused by the lens, and lands onto the retina. The retina uses this light to form an image that is transmitted to the brain via the optic nerve.
If our eyes had no lenses, light would enter the eyes and land on the retina from every direction, making for a very blurry image.
The eye’s lens helps focus light and form it into a sharp image onto the retina.
The optic nerve transmits the visual information from the retina to the brain, which is what allows us to see.
Whenever you look at an object, you’ll realize that the background and foreground are blurry while the object you are looking at is in focus. This happens because the eye’s lens can only focus light coming from one distance. This is called the eye’s focal length. Objects too near or far are perceived as out of focus.
Fortunately for us, our eye’s muscles can contract or expand the lens so it can change the focal length, allowing us to see clearly at various distances.
Pinholes, by their very nature, limit the amount of light that can enter the eye. This helps block out extra light noise that would otherwise create a blur. Thanks to the small opening, light streams into the eye from a focused direction. So your hand becomes an impromptu lens. Less light bouncing around inside the eye means that looking through a pinhole inherently keeps things in focus.
By looking through the pinhole you create with your fingers, you are limiting how much light is entering your eye, thereby “filtering” the excess light that would otherwise blur your vision.
Disadvantages to using pinhole vision, however, are that it does also mean less light getting through to the eye, as well as a severely limited field of view. Less light means that your vision while looking though a pinhole is darker.
But when push comes to shove, using this method for even limited focused vision is a nice tool to have in the proverbial toolbox. In a SHTF situation, it could mean having the ability to tell if that dark blob 30 yards away is an abandoned car or a band of marauders lying in wait.
Because walking around with your hand to your face can get a bit annoying, we suggest keeping backups of your eyeglasses stored away in case you get separated from your primary set. Keep an extra pair or two of your prescription glasses in your bug-out bag or an alternative location, such as at work or in your vehicle. Even older prescription glasses can be of some help versus not having glasses at all.