Blur to Clear Flashes – The Progression
You are using your lowered prescription, you are pushing / pulling focus at your blur horizon, and suddenly, everything around you is clear, for a few moments. You notice this very intermittently at first, but as you get better distance with your reduced prescription, the flashes happen more frequently, and tend to persist longer.
And the reason for this is not some spontaneous change in your eyes. Axial and ciliary myopia take time to resolve, and most of your improvement experiences tend to be very, very gradual.
Gradual, except for the clear flashes.
While these will seem very encouraging, miraculous even, the explanation is fairly simple:
Clear flashes are not a product of sudden resolution of ciliary or axial myopia. Instead, clear flashes happen when a double vision image is resolved (by your brain, in the visual cortex), into a single, clear image.
In other words:
When your surroundings are actually blurred, you will not experience clear flashes.
Rather, when what appears to be blur, is actually multiple clear images, not aligned as a single image, become aligned – which is accomplished in your brain, rather than in your eyes. You did all the ground work to reduce strain, cause positive stimulus, reduce focusing muscle spasm, maybe even reversed some axial elongation. Now you are almost there, except that the improvements in your two eyes rarely ever happen precisely synchronized.
So, when you reduce that ciliary (focusing muscle) spasm, it will not happen identically, at the same time, in both eyes.
When axial elongation reverses, it rarely happens at the exact same rate, in both eyes.
Your eyes are two separate biological constructs, and as such they are never perfectly even. You know this, by the fact that likely your prescription is not the same, for both eyes. You know what happens though, to compensate for this biological imperfection?
Your brain (visual cortex) compensates for imbalances between your two eyes.
This is something you can check for yourself, no leap of faith for Alex required. Here is how:
Measure your eyes, using the myopia calculator.
Of course you will find some small difference between the distance you get with your left, and your right eye. So if your brain would not compensate, what would happen?
You would get two images, one weaker, one stronger. Since that is what your eyes are sending as signal.
When you look with just the left, or just the right eye, you get different distance results. But when you use both eyes? Suddenly the result is whatever your better eye produced alone, or even better than that (especially on the Snellen chart). And it isn’t just your brain taking out the weaker eye results – otherwise you would have no depth perception. Instead, your visual cortex combines the data sent by your eyes, and interprets it, into the best possible vision for you.
This happens in fractions of a second, without you even noticing.
And this is, because your brain already has an expectation, knowing full well the differences between your eyes. Basically, the brain is already set up to compensate for the small biological differences between your left and right eye.
But then, what happens when you improve your eyesight?
Now suddenly, these differences are no longer the same as they used to be. And your brain, does not know how to compensate for this change.
Incidentally, this is why you frequently see me talk about the hazards of prescription complexity, and why we want the simplest glasses prescription possible – complexity causes your brain to adjust for artificial focal plane induced (ie. your glasses) change. The more artificial change, the poorer your vision is without glasses, and the more your dependency on glasses increases.
And the result?
Double vision. Read up on double vision vs. blur, if this is not yet a familiar topic.
This is a bit of an advanced subject in the Vision Improvement Course (60s installments), which cover double vision, and these clear flashes, in some details.