In this topic I’m providing you with a very crude, grossly oversimplified, but hopefully insightful visual explanation of how and why double/misaligned vision occurs. Keep in mind that in reality this all happens three dimensional and that this is nothing more than a schematic representation.
First you see the emmetropic eye nicely bundling the rays of light bouncing of an object (A sign with “respect the beard!” in this case) being refracted properly into focus on the retina of the eye. As you can see, it’s all combined nicely into a single focal point on the retina and the visual cortex gets nothing but a clear image presented enabling you to see the text in complete clarity.
Next we see the myopic eye. What’s evident is that this refracted bundle of light starts to diverge again before hitting the retina. This means that the rays of light end up being spread out across the retina. By not having the object one’s looking at combined into a nice single point the rays of light get dispersed creating multiple images relayed by the retina and it’s peripheral area. Some of the light will still combine nicely in some places on the periphery creating those multiple images that you can see if you’re familiar with double/misaligned vision. This is depicted with number 2.
Some variations on this phenomena are shown with the following numbers:
Very close to completely aligned vision, only a small portion of the light is out of place creating is small haze surrounding the text/object one’s looking at.
The most common version of double/misaligned vision.
A more potent and aggressive version of misaligned vision. The light is much more dispersed making it much tougher for the eyes and visual cortex to align this properly. This usually occurs when someone is under-corrected by too much or there isn’t enough good lighting available. Having ciliary muscle spasm can also be the cause of this happening to a greater extend.
In this case there is enough light that intersects properly and comes into focus on the retina, however there are many rays of light still getting severely spread out causing a big haze surrounding what someone is looking at. Many times this is a sign that improvement is happening after reducing ones normalized correction and that our eyes and visual cortex start adjusting to bring that bundle of light into a properly focused bundle.
This is pretty much how and why blur happens. That bundle of light is dispersed by so much that there’s hardly any light combining properly onto the retina or it’s periphery. There is only blur to be registered by our visual cortex and no workable image can emerge from this data.
Keep in mind that all the varieties shown in this explanation and the manner in which any of them can occur greatly depend on three main things (amongst others of course):
- How much the distance the actual distance is between that focal point and the retina
- The ability of the ciliary muscle to relax properly to get that focal point in the right spot
- The way ones peripheral vision is utilized. An important part of Endmyopia is getting that peripheral vision working properly again. The more “developed” it is, the more it’s able to make out what gets projected onto it’s surface.
Thanks to Jake (of course) for checking this!
If you want to work on improving your misaligned vision, we have a nice guide for you right here: Resolving Double/misaligned vision.