Originally posted by Sky01
1) Focussing on near objects causes stress on the eye
2) This stress can deform the eye
3) This deformation is treated with eyeglasses
4) These eyeglasses only bring things nearer to you (virtually, but real enough for the eye muscles)
5) This increases stress, increases deformation, increases prescription, cycle
Retinal detatchment, etc, and essentially incapacitation without glasses.
Um, sort of. I agree with 1, 3 (sort of), 4, and 5 (sort of).
For some people, long term near-point stress will cause ciliary muscle changes that are semi-permanent.
Also, and this is something you don't hear a lot about, your eye has the capacity to lengthen under certain types of stimuli. It's slow but it
happens. The degree and speed at which this occurs is likely also genetic.
Definitely, one of these stimuli is low light conditions, oddly enough. If you are indoors all the time, your eyes will lengthen. Going outside and
"sunning", something that Bates used to advocate, neutralizes one of the enzymes in the signaling cascade for eye lengthening, so it actually has
I would be surprised if constant near-point adaptation didn't cause it as well, although I haven't read any studies on it.
As far as glasses and progressive myopia goes, there are some very fascinating studies that are fairly recent that explain that in a way that actually
A prime stimulus for long term eye lengthening/shortening has been discovered to be the focal plane in your peripheral vision. If the "in focus"
plane for your peripheral vision is in front of the retina, your eye will over time become shorter until your peripheral vision is in focus. If the
"in focus" plane is behind your peripheral retina, your eyes will lengthen.
The problem comes in with the way your glasses or contacts are made. They focus the image at your fovea, where your detailed central vision occurs,
but they typically place the peripheral focus behind your retina. This causes your eyes to lengthen in response, as your eye tries to reshape itself
to match long term changes in your natural optics. As this happens, the foveal focus will move forward in front of your retina, and your glasses
"won't be strong enough anymore". So you get new ones...and once more the peripheral focus moves behind the retina, and your eye grows even longer
This is the hotly debated new theory - it actually makes sense and there are some pretty good studies that seem to back it up.
There's no real reason you can't design glasses or contacts to maintain peripheral focus, or even to place the peripheral focus in front of the
retina while holding the focus at the fovea, which should cause progressive improvement instead of progressive myopia, if the theory is true. They
just don't, or at least, haven't up until now.
CooperVision is getting patents on it for contacts (see also MiSight contacts), and I've heard some of the lens guys are looking at it for glasses.