No relationship found between accommodative lag and myopia progression

We’d wondered before, now someone has done the research:

https://www.nature.com/articles/s41598-020-68859-6

By adjusting for age and SER, it was shown that the myopic progression rate was not associated with the accommodative lag (F = 0.269, P = 0.604), accommodative lag area (F = 0.086, P = 0.354), slope of ASRC (F = 0.711, P = 0.399), and DAF (F = 0.619, P = 0.432).

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I read the introduction and the discussion. Apart from the lack of association between accommodative lag and the progression of myopia, there were some other conjectures/hypotheses raised that interested me.

There will be a lot more reasearch on myopia coming out of China - a small piece of the puzzle at a time.

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I was trying to understand what accommodative lag means from the introduction, but it doesn’t appear to be defined anywhere in the paper.

Searching the forum lead me to a mention in this glossary but sadly it hasn’t been defined there either. Many other posts refer to that concept without defining it, so I’m guessing it’s a common concept in EM, but the best I could find was this post on accommodation which define accommodation, but not accommodative lag.

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Accommodative lag is not an EM concept. It means the time it takes to adjust accommodation from near to far vision and vice versa. It has been measured to be slower in myopes than emmetropes, and was hypothesised to be one of the causes of myopia progression. This study attempts to show that it is not the accommodative lag in myopes that is associated with myopia progression.

A google search would have put you on the right track.

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Interesting. Just to geht it clear: It was tested, wether the (to put it in simple words) speed of the ability to focus from far-away to close-up or vica versa may be related to myopia progression, right? What is the concept behind this? I didn’t get that from the article.

" Moreover, myopic children tend to read at a closer distance when compared to emmetropic children11, which may lead to increased lag of accommodation, as lag increases with accommodative demand1"
I thought that to be quite interesting, isn’t that the phenomena EM would describe as “ciliary spasm”? --> Lens reacts to increased close up and thus focusing clear in the distance gets difficult (at first only for a few minutes and then turns clear - and with time myopia worsens as eyeball elongates to adapt). Or was the premise that the children hold books so close because of accommodative difficulties? That seems odd for me to think that, as at least from own experience that was never the case for me - it is just a bad habit to have stuff close and often related to a more comfortable sitting position… I can/could see everything just as well when holding the book/phone further away.

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Yeah it is. From Endmyopia perspective it seems to be obvious: you have ciliary spasm because of the full time correction, and most myopic people are full time corrected, so most myopic people will have accomodative lag. But the accomodative lag is a symptom of the full time correction and not myopia.
But I’m glad that they could prove it scientifically :slight_smile:

Edit: for clarification, they only proved that accomodative lag is not the cause of myopia. They did not proved (nor explored) that (too much) correction causes accomodative lag.

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One can have ciliary spasm without any correction, as is the case in pseudomyopia. I think the fact that I use no correction does not protect me from ciliary spasm from hours of close vision.

This is not what the study set out to prove. It was looking at accommodative lag and myopia progression. In no way did they show, let alone prove, that accommodative lag is caused by wearing full myopia correction. This does not preclude it as a possibility. From the little I have read, the accommodative lag sets in some years after myopia, but there is no way of knowing without further comparison between never corrected and corrected myopes if it is caused by correction.

Accommodation is measured in diopters per second and can be improved with vision therapy exercises, but the study above also questions whether this is of any use in halting myopia progression, as they found no correlation between the two. I suspect this has little to do with ciliary spasm.

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You are right, I’ve rechecked my comment and added some clarification.

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I need to research this. Sounds interesting.

I think maybe the connecting link could be that “holding stuff too close for too long” (and too little use of distance vision) is the reason for ciliary spasm/accommodative lag - and that can be unrelated to wearing correction. Though wearing correction may aggravate the situation even more. Would be interesting to see a study look at that.

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This study sheds some more light on the topic.
Discussion
The results of this study clearly demonstrate that the
accommodative lag which appears under a habitual seeing
condition can be different from that under an experimental
condition, ie, monocular viewing after full correction
with contact lens.3,4,6 Therefore, the previously reported
data obtained under the experimental conditions are not
sufficient for discussing the causative relationship between accommodative lag and myopia progression.

Also: In an environment close to natural seeing
conditions, ie, binocular viewing through habitually worn
glasses or contact lenses, we failed to demonstrate a larger
accommodative lag in adults with EOM than in emmetropic adults. ( EOM refers to early onset myopia.)

It seems I cannot link the article, but this is the title:
Accommodative Lag Under Habitual Seeing Conditions:
Comparison Between Adult Myopes and Emmetropes
Chiaki Nakatsuka, Satoshi Hasebe, Fumitaka Nonaka and Hiroshi Ohtsuki
Department of Ophthalmology, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan

You can probably access it yourself. It would seem to indicate that the wearing of correction in myopia may not much affect accommodative lag. This assumes that most myopes are slightly undercorrected, which is probably not always the case. Anyway, it shows us that experimental conditions do not always relate to real life conditions, and we should take all experimental studies with a pinch of salt.