Did you ever notice your vision getting significantly worse in the (late) evening? You’ve had a good day vision wise. Active focus happened easily and automatically all day and there was no significant amount double vision. Then suddenly in the evening while watching TV you start to notice considerable double vision. You just can’t get those subtitles to clear up no matter how much you try to use active focus. Trying only seems to make it worse. So, what happened? Did your eyes suddenly get worse? Of course not. There is obviously a lot less light in the evening, but on other evenings that didn’t cause any big problems for your vision. Now, if you’ve spent a lot of time looking at a (phone) screen that day, the answer could be a ciliary spasm. But what if you haven’t? What if you spent most time outside practicing active focus and getting lots of distance vision? The answer is obvious, but easily overlooked. You’re just tired! Practicing active focus for an extended period of time will cause fatigue. Some people say “my eyes are tired”. That’s probably true. All muscles get tired after intensive use, so the eye muscles are probably no different in that respect. But what is often overlooked is the brain!
The amount of processing that happens in the brain is just astounding. Your visual cortex is constantly processing images from both eyes, compensating for any imperfections in the images received though the retina, filling in blanks, and combining the images from both eyes into what we perceive as one 3D picture. And all of this happens in real time, from millisecond to millisecond. You probably know it takes a pretty powerful computer and graphics card to get smooth real time image processing. Well, the brain does all of that and much, much more. While the visual cortex handles the image processing, the part of your motor cortex that is responsible for the eyes constantly causes your eye muscles to direct your eyes to whatever it is you want to look at, converging and diverging the angle between your eyes, focusing your lens, contracting and dilating you pupil to adjust to needs of each moment. Just think about the amount of energy needed for all these tasks. And I’ve only discussed some of the things concerning vision. But all other bodily functions are also regulated by your brain! And now you’re adding even more to that workload by walking around under corrected and basically telling your brain: “I don’t care how you do it, but you’d better make sure those images are clear!” Your brain can and will do this to the best of its abilities, because that’s its job, but it will eventually get tired (especially when you’ve just reduced your prescription)… The role of the brain is something we tend to take for granted. We usually are totally unaware of all the image processing that goes on there, unless something goes wrong (we suddenly get double vision for instance) or we are confronted with some optical illusion devised fool the brain.
When people start out on this vision improvement journey they usually focus completely on the eyes and the physical aspects of vision. I know I did… But our visual system is more than just our two eyeballs. The brain is where the real magic happens! Bates understood this and put great emphasis on mental aspects of vision (I intend to write another post about some of the important insights of Bates soon). My point for now is: when the brain is tired, all mental processes (including the image processing in the visual cortex) slow down and glitches become more and more frequent. So, when you notice your vision getting worse in the evening and those subtitles getting harder to read, take this as a sign that your brain needs rest. Instead of trying harder and harder to get active focus to work again, turn off that TV and go to bed. And don’t worry about what might feel like a setback. You’ll find that after a good night of sleep everything will work again just fine.