Optician here. I wanted to make some points about misconceptions in the comments. Eye exercises DO work. Just how much you improve depends on a lot of factors. What exercises you need can best be determined by an orthoptician which is basically a specialised eyedoctor for binocular vision/ training. Exhausting your eyes (being ill, doing close-up work without resting,...) makes for weaker eyes needing more power. Eye tests done are mostly done via a set routine, however are entirely subjective. A difference of .25 is the smallest difference we can change and is barely noticable for most. Not every person measuring will make the same decision, but double checking should happen with every measurement. Your state of mind can alter your vision. Being relaxed, intoxicated, pregnant, you name it, can and will affect the necessary power for 20/20 vision. Another myth is that wearing correct glasses makes your eyes weaker. Wearing the wrong power however, can make your eyesight worse. I suspect this is because loads of people wear wrong prescriptions, or use them (and their eyes) in the wrong ways. Another part is consumerism. An optician 's business is selling you glasses. Not everyone is honest about you not actually needing new glasses. Lastly: Pinhole glasses do work. They do this by reducing incident light to a single beam. This beam focusses more tightly on the retina, producing sharper images with lower brightness. This is also why people with very small pupils will generally see better in light conditions.