Short-term Response Differences between Emmetropes and Myopes

Emmetropes and myopes were subjected to an hour of blurry movies (either through plus lenses +2.5D or reduced corrections for myopes; or through computer generated blur.)

The myopes’ eyes elongated in response to the myopic defocus while the ememtropes’ eyes got shorter.

Possible implications for us are that large attempted reductions (2.5D in this case) are counter-productive in myopia, but near-emmetropes or (very low myopes) might be able to benefit from larger amounts of myopic defocus stimulus.

Another possibility is that myopes have stopped trying to clear blur, but emmetropes do it all the time. [???]

The lines on the chart represent individual participants in the study. Almost all of the emmetropes are moving in the “correct” direction in response to the 2.5D myopic defocus stimulus (eyes getting shorter). Most of the myopes are getting worse after 60 minutes of 2.5 D myopic defocus. The computer-generated blur (middle column of charts) made everyone’s eyes worse except for one myope’s whose eyes got shorter.)


That is interesting. Ursa was managing but it would appear she was the exception, and that the rule is that (as we already knew, but to an even greater extent than we realized or at least than that we had a study to back up) too much blur is in fact counter productive to the process.


The study is really interesting but they’re also just looking at changes after one hour of watching a movie on a big screen TV at 2 meters distance. It’s possible that weeks or months of that stimulus would do something different (although I kind of doubt it), or that being outdoors in the sun with that amount of under-correction would show different results. (Nobody really knows until somebody studies it to see what happens, but I would guess that being out in the sun makes the emmetropization process work more like expected.)

It wouldn’t surprise me if people can get away with bigger under-correction out in good natural light, but a 2.5 D reduction is way too much.


It does seem unlikely that the trend would turn 180 degrees and go back the other way.

As I demonstrated in my 2nd video on measuring you can get away with less correction outside on a sunny day, but only to a point. After a certain distance beyond your larger diopter bubble things start lining up with your indoor measurements. So on the 20 foot chart with lenses that get you 20/30 indoors you will measure 20/20 and probably 20/15 at 20 feet but at say 40 feet you lose the crispness on the 40 foot line that would equal 20/20 vision, beyond that the trend continues so at 100 feet you really only get the 20/30 (though moderately better clarity) equivalent as per your indoor measurements. Which is why I always object to the 20/50 “rule” for normz, then you have too many people driving around below the legal requirements because they think they are seeing 20/25-20/30 but they really aren’t… Besides I am squarely in the camp that 20/50 is too much blur, but I suppose everyone knows that by now :smiley:

Edit: All of which assumes you are doing your measurements accurately in the first place, which in many cases people are using active focus or above expected lighting (for normal circumstances). In which case they are more 20/60 when they think they are 20/50 and that starts getting hair scary to consider they are then driving :scream: I have even seen a few times people have suggested that getting 20/50 means time to reduce, I can’t imagine why so many people are suffering intense DV with misconceptions like that :roll_eyes:


Some individuals have improved by going no correction.


I sure am with you on that, since 20/50 is what I am uncorrected. And 20/50 is exactly what I’m trying to get away from!