Author Topic: Don't overdo the blur  (Read 2172 times)

Offline CapitalPrince

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Don't overdo the blur
« on: February 01, 2015, 10:39:54 PM »
some people have had success with strong blur, but if you experienced no progress, you might be reading through too much blur.

Todd, Dr. Frauenfeld, Jake Steiner, David De Angelis, all recommend a very slight blur and expresaed that too much blur may cause the eye to give up.

I think one of Todd's posts on "Eyesight without glasses" is excellent
"Let us distinguish three distances:

D1. The 'edge of focus' which we'll define as the furthest distance for myope (or closest for a hyperope) where a printed letter is completely in focus
D2. The 'edge of blur' which we'll define as the distance just beyond the edge of focus, where a slight blur in the letter can just be detected
D3. The 'edge of readability' which we'll define as the furthest distance where you can intelligibly recognize what the letter is.

Now D1 and D2 are going to be VERY close, almost exactly the same distance. If you are reading at D1, and you push the print slightly away less than an inch, you are immediately at D2. And if you are at D2 and get the tiniest distance closer, you are back at D1 again.

But D3 (which is what I think you are calling "the edge of blur", but is really beyond that) might be a fair distance away, perhaps even several inches (for small letters) or several feet (for large letters).  And D3 will also depend on your familiarity with the letters and the language.  You can "guess" a blurry word like "eye" because you know the English language, whereas if it is a word in a different language you might not be able to read it.  So D3 depends on the size of the letters and your ability to recognize the letters and words.  D3 depends upon your brain, not your eyes. You might be able to read a very blurry version of the word "eye" and guess it, whereas a non-English speaker might guess the wrong letters.

To get the benefit of plus lenses, your eyes must be working "automatically" to try to focus, so they must be able to detect the direction of defocus, that is, whether the blur is caused by being too close or too far.  Your eyes detect this defocus right within the retina -- the back of your eye.  This detection process does not involve your higher brain functions that are involved in word recognition or trying to guess what a word means.  So you must allow the eye itself to detect the defocus.

Therefore, ideally your focal distance should be at D2 -- the edge of blur. This should be the slightest blur detectable, and it is even OK to move back and forth between D1 and D2 to keep "testing" this distance.  If you go beyond D2 to D3 (the edge of readability), you are now at a place where your brain is doing the work of guessing, but the focus detection system in your retina is no longer able to detect the direction of defocus. It's not just that the eye muscles and lens "give up" trying to focus, its also that you lose any stimulus for change of the structural tissue around the focal plane at the back of your eye (the retina).  So your eye gets no information about how it needs to change."

Offline Alex_Myopic

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Re: Don't overdo the blur
« Reply #1 on: February 02, 2015, 04:45:38 AM »
Nice post. I agree by practice. I have even tried shocking the eyes with strong plus (far beyond the edge of blur) and didn't see results with that. Maybe if someone is cooking for hours some mild plus might help him if he doesn't do much outdoor activity, even if he isn't at the edge of blur.

Offline CapitalPrince

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Re: Don't overdo the blur
« Reply #2 on: February 02, 2015, 08:20:22 AM »
i have several pairs of plus lenses from the drug store. mostly i just wear a +2 all the time and look over when necessary. with the +2 i can read comfortable at around 50 cm with a slight blur.

Offline HansK

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Re: Don't overdo the blur
« Reply #3 on: February 02, 2015, 08:57:58 AM »
When trying to focus, (sometimes) the image clears up and when I blink, I lose focus -- the slight blur comes back again.

Is that okay that I lose focus after blinking or am I doing wrong?

And: Does it have to clear up or is it okay that there is always a slight amount of blur?

Kind regards,
Hans

Offline Alex_Myopic

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Re: Don't overdo the blur
« Reply #4 on: February 02, 2015, 10:23:51 AM »
There should always be a slight or medium amount of blur. Me too I see more clearly if I blink hardly mainly but this is an extra thing too do if you believe it helps and it is also in the PVS program.

Offline HansK

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Re: Don't overdo the blur
« Reply #5 on: February 02, 2015, 10:50:34 AM »
No, I do not have to blink hardly to clear the blur. It happens unconsciously -- the feeling is as if my pupils would change due to more lightning.