Accomodative Excess, a cause of Myopia?

Just ran across this article:

Basically, when presented with near work, some people use more accommodation than should be necessary to view the object. Excessive near work is a predisposing factor. It’s listed as a possible cause of Pseudomyopia.

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Related:

This is my bad habit as my past closeup position was to stick my eyes to around 4 inches away from paper while writing. it just helped me concentrate on answering exams. That was definitely a stupid habit. :frowning_face:

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Me too! I had the same stupid habit! :frowning_face:

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No, not moving your body closer, this is when object is already close enough to focus, but the ciliary tightens down even more than it needs to to focus. The image would actually get slightly less clear.

But if I understand correctly the mainstream optometrist does not say that accomodative excess causes pseudomyopia. Rather that in pseudomyopia the cause is not ciliary spasm, but accomodative excess: the image focuses before the retina because the ciliary is contracted more than it should.

Also I don’t think it can cause myopia, because practically it causes myopic defocus. So if it can cause anything then it’s hyperopia.

Or I misunderstand something?

Hrm… We are coming around to a prior discussion… Hyperopic defocus is frequently touted here as a cause of myopia, but near work doesn’t cause defocus, it causes acomodation to avoid defocus. So if it’s acomodation that causes myopia and lack of acomodation that causes hyperopia, then the action of the ciliary is more important than the actual distance of the work or amount of focus.

I still think that by “hyperopic defocus” Jake means “accommodation to hyperopic defocus”. Or if he don’t, he should be :slight_smile: Especially because “myopic defocus” alone is not enough for improvements (ie.: ditching glasses), but “accommodation to myopic defocus” (AF) is needed. But if I understand correctly you agree on this.

But I still don’t understand how accommodative excess fits into the big picture. Or I can fit into if I use it as a synonyme for “ciliary spasm”, but in that case it’s nothing new. Some other sources supports this, like:

But if it’s not ciliary spasm then I can only understand it as an “overfocusing” which would mean that the vision is blurry in close-up. But this definitely not happens for myopic people, at least I don’t know anyone who had this problem and later developed myopia.

So I’m still not sure if either:

  • I’m missing something
  • I’m just too dense today
  • It’s just a different name for ciliary spasm :slight_smile:

I think you’re right that they’re essentially the same thing, but what’s new here is a method of measuring it.

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Less unpleasant than cycloplegia.

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I presume you mean the link in your second comment? Where they put some text 40 cm away from the subject and then add plus lenses until they see blur? Isn’t that the same as cm measurement, just instead of changing the distance they change the correction?

Dynamically changing the lens challenges the ciliary to change more than a static measurement.

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But cm measurement is not static. You should get really close (so it’s 100% sure that you accommodate) and start to get back until you reach the edge of blur. For me it means head movement of 20+ cm for a measurement. Of course for high diopter is much less, but I think the plus lenses method would also result in only 1 or 2 lens in those cases.

I don’t move my head, I slide my card on the ruler, and certainly don’t need 20cm of movement to find the right places for the two measurements of my left eye. For my right eye cm measurements are no longer practical, and here the lens challenge might be more informative. I am not all that interested in my right eye measurements at present.

The advantage of the plus lens measurement method can be seen in your case though :slight_smile: Because cm measurement is not possible for you, but with the plus lenses it should be possible to measure. Of course you would need a test lens kit for that, and I don’t think it worth it, so just theoretically :slight_smile:
So yeah, in this way plus lens measurement method is better, because it’s useful / practical for low myopes too.

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