Author Topic: Online test for astigmatism  (Read 21277 times)

Offline OtisBrown

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Re: Online test for astigmatism
« Reply #30 on: March 17, 2013, 10:16:56 AM »
Hi John and Phillipp,

I agree that in principle - this should be a separate thread.  But we will always get into these conversations "backward".

What concerns me with Philip (not a criticism) is that he has a "spherical equivalent" of -3.0 diopters (or a focal length of 13 inches, or 33 cm - which indicated he should have 20/200 vision or worse), and yet he seems to be able to read most of the letters on the 20/60 line.  That means to me, that he is grossly over-prescribed.  That is why I "convert" to "spherical equivalent" for the comparison.  If he does read the 20/60 line (he said he can read the 32 foot line) then he is indeed over-prescribed.  The fact that he can read ANYTHING through a plus lens - again proves he is over prescribed.  If he was a TRUE -3.0 diopter myope - he  could see nothing at 20 inches through a plus lens.  Because of the gross errors in measurements - that I include a video on how to CHECK AT HOME.  Phillipp has not posted on other threads - so he may as well learn to check 20/60  here.

As always - I enjoy these conversations - but agree that it take intense long-term motivation to get your Snellen to clear from 20/50 to 20/20.  Most people "fade" after a week or two.  Only the most self-motivated will STICK with reading their Snellen - to get it clear under their PERSONAL control - in my opinion.  I just show HOW to do it - if the person is interested.


If you give the person the POWER TO MAKE THE MEASUREMENT - YOU REMOVE FROM THE PERSON - THE FEAR OF THE MEASURMENT. That is my philosophy in pure science.

I agree.

Offline johnlink

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Re: Online test for astigmatism
« Reply #31 on: March 17, 2013, 10:23:58 AM »
What concerns me with Philip (not a criticism) is that he has a "spherical equivalent" of -3.0 diopters (or a focal length of 13 inches, or 33 cm - which indicated he should have 20/200 vision or worse), and yet he seems to be able to read most of the letters on the 20/60 line.

Otis, the anomaly you observe is resolved by noting that in his first post on this forum Philipp wrote that he has gone from 20/60 to 20/30 and that he is no longer wearing the glasses with a spherical equivalent of -3 D. Have a look:

Hello John,

After 7 months of not wearing my prescription glasses I have improved my snellen from 20/60 to 20/30 but my -1.75 of astigmatism hasn't changed at all, which makes it impossible for me to see a clear image at any distance, which means I can't push print effectively. I tried the eye exercises for a few months but didn't notice a difference, I am beginning to think astigmatism is permanent.


But of course -3D would be quite an over-correction for someone with 20/60 vision.
« Last Edit: March 17, 2013, 10:52:07 AM by johnlink »

Offline PhilippK

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Re: Online test for astigmatism
« Reply #32 on: March 17, 2013, 10:31:47 AM »
Hi Otis,

I just printed a standard snellen from i-see and in sunlight I was able read every letter on the 20/25 line with a couple of light blinks, it wasn't crystal clear but I saw it. It looks like I am making more progress than I realize, do you think too much convergence is the main culprit for astigmatism?

Offline johnlink

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Re: Online test for astigmatism
« Reply #33 on: March 17, 2013, 10:35:01 AM »
I just printed a standard snellen from i-see and in sunlight I was able read every letter on the 20/25 line with a couple of light blinks, it wasn't crystal clear but I saw it. It looks like I am making more progress than I realize

Congratulations!

Quote
do you think too much convergence is the main culprit for astigmatism?

Why do you think that might be the case?

Offline PhilippK

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Re: Online test for astigmatism
« Reply #34 on: March 17, 2013, 10:52:55 AM »
Quote
Why do you think that might be the case?

John,

If I look out with just my right eye objects bleed out to the right and objects bleed to the left with just using my left eye, so its the inner portion of my eyes closest to my nose that give a less distorted image. I don't know just thought that may have something to do with converging too much.
« Last Edit: April 16, 2013, 05:13:08 PM by Todd Becker »

Offline johnlink

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Re: Online test for astigmatism
« Reply #35 on: March 17, 2013, 10:59:10 AM »
If I look out with just my right eye objects bleed out to the right and objects bleed to the left with just using my left eye, so its the inner portion of my eyes closest to my nose that give a less distorted image. I don't know just thought that may have something to do with converging too much.

Have you discussed that with your OD? I don't experience anything like that, nor have I ever heard of it. I wonder whether you might have some sort of irregularity not fully described by astigmatism.

Offline OtisBrown

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Re: Online test for astigmatism
« Reply #36 on: March 17, 2013, 11:13:44 AM »
Hi Phillipp,

Subject: I believe we should be EMPOWERED to make all critical measurement - personally.

Regarding:  Meeting the objective REQUIREMENTS for flight - from the FAA.

My strong desire it to avoid wearing a minus lens.  To achieve that goal - I must exceed the FAA 3rd and FAA 1st REQUIRMENTS - OBJECTIVELY.

The FAA 3rd is for 20/40 in both eyes.  Thus I MUST make this measurement myself - just to be safe.  You are exceeding the FAA requirement.  It is your option if you wish to wear that -3.0 diopter lens all the time - or no lens at all.  You will EXCEED the DMV requirement - since you have 20/25 vision.  If you have not yet done so - I would go down (at your convenience) as pass their test - if you wish.

If you wish further Snellen clearing, then I would just continue wearing that plus lens for the close-work you are now doing.  Todd did it, and it is very reasonable that you verify your vision yourself - as I do it.

But you might find it interesting (and wise) to order your own -1.0 diopter lens from Zennioptical.com - just to see how that "improves" your Snellen.  I am a practical engineer. It would be a good check for you.  I suspect you could read the 20/18 line THROUGH a -1.0 diopter lens.  In fact, you could wear that "minus" at night - if you wish.  But you now know where you stand.  I believe in intelligent self-checking - and that is how *I* would do it.

Hi Otis,

I just printed a standard snellen from i-see and in sunlight I was able read every letter on the 20/25 line with a couple of light blinks, it wasn't crystal clear but I saw it. It looks like I am making more progress than I realize, do you think too much convergence is the main culprit for astigmatism?

Offline PhilippK

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Re: Online test for astigmatism
« Reply #37 on: March 17, 2013, 11:24:24 AM »
If I look out with just my right eye objects bleed out to the right and objects bleed to the left with just using my left eye, so its the inner portion of my eyes closest to my nose that give a less distorted image. I don't know just thought that may have something to do with converging too much.

Have you discussed that with your OD? I don't experience anything like that, nor have I ever heard of it. I wonder whether you might have some sort of irregularity not fully described by astigmatism.

I should have used the word blurred instead of bleed, it not extreme as I may have made it sound, but if i look at the blue lit circle around my monitors power button with just my left eye the left side of the circle appears SLIGHTLY more blurred than the right side of the circle and vice versa with the other eye. When I fuse the circle with both eyes the blur or bloom is less noticeable all around.

Offline johnlink

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Re: Online test for astigmatism
« Reply #38 on: March 17, 2013, 11:28:42 AM »
I should have used the word blurred instead of bleed, it not extreme as I may have made it sound, but if i look at the blue lit circle around my monitors power button with just my left eye the left side of the circle appears SLIGHTLY more blurred than the right side of the circle and vice versa with the other eye. When I fuse the circle with both eyes the blur or bloom is less noticeable all around.

Have you discussed this with your OD?

Offline OtisBrown

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Re: Online test for astigmatism
« Reply #39 on: March 17, 2013, 11:40:45 AM »
Hi Phillipp,

Subject: I used you as  an example of severe -3.0 diopter over-prescription.

When I state that many people are over-prescribed - no one believes me.  The fact that you have a "spherical" minus of 3 diopters - and have managed to clear the 20/25 line - tells me that a "mix" of a bad astigmatism measurements and an over prescription minus created your -3 diopter prescription.

This is why I ask a person who wants to become a pilot - to do this Snellen checking.  You probably do have a slight degree of astigmatism - but you can do everything you wish with no lens for distant vision.  That is MY GOAL.  I don't mind doing close-work by reading through a plus.  But I hate being DEPENDENT on a minus for distant vision - and will do everything I can to make certain I exceed the required DMV line.

I wish I could give you a "Jackson cross cylinder" test frame.  I think you would find your astigmatism is must less that you might imagine.  But that would be for future study and analysis.  For now, I am very pleased you are at 20/25 - far about the required 20/40 line for driving a car.

 CONGRATULATIONS ON YOUR OBVIOUS SUCCESS WITH THE PLUS FOR NEAR!!


Hi Otis,

I just printed a standard snellen from i-see and in sunlight I was able read every letter on the 20/25 line with a couple of light blinks, it wasn't crystal clear but I saw it. It looks like I am making more progress than I realize, do you think too much convergence is the main culprit for astigmatism?

Offline PhilippK

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Re: Online test for astigmatism
« Reply #40 on: March 17, 2013, 11:46:11 AM »
Hi Phillipp,

Subject: I believe we should be EMPOWERED to make all critical measurement - personally.

Regarding:  Meeting the objective REQUIREMENTS for flight - from the FAA.

My strong desire it to avoid wearing a minus lens.  To achieve that goal - I must exceed the FAA 3rd and FAA 1st REQUIRMENTS - OBJECTIVELY.

The FAA 3rd is for 20/40 in both eyes.  Thus I MUST make this measurement myself - just to be safe.  You are exceeding the FAA requirement.  It is your option if you wish to wear that -3.0 diopter lens all the time - or no lens at all.  You will EXCEED the DMV requirement - since you have 20/25 vision.  If you have not yet done so - I would go down (at your convenience) as pass their test - if you wish.

If you wish further Snellen clearing, then I would just continue wearing that plus lens for the close-work you are now doing.  Todd did it, and it is very reasonable that you verify your vision yourself - as I do it.

But you might find it interesting (and wise) to order your own -1.0 diopter lens from Zennioptical.com - just to see how that "improves" your Snellen.  I am a practical engineer. It would be a good check for you.  I suspect you could read the 20/18 line THROUGH a -1.0 diopter lens.  In fact, you could wear that "minus" at night - if you wish.  But you now know where you stand.  I believe in intelligent self-checking - and that is how *I* would do it.

Hi Otis,

I just printed a standard snellen from i-see and in sunlight I was able read every letter on the 20/25 line with a couple of light blinks, it wasn't crystal clear but I saw it. It looks like I am making more progress than I realize, do you think too much convergence is the main culprit for astigmatism?

I just checked with a -1.25 spherical and I can see no more than 20/20 beyond that the letters are too small and jumbled.

Offline PhilippK

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Re: Online test for astigmatism
« Reply #41 on: March 17, 2013, 11:52:53 AM »
I should have used the word blurred instead of bleed, it not extreme as I may have made it sound, but if i look at the blue lit circle around my monitors power button with just my left eye the left side of the circle appears SLIGHTLY more blurred than the right side of the circle and vice versa with the other eye. When I fuse the circle with both eyes the blur or bloom is less noticeable all around.

Have you discussed this with your OD?

No I haven't. I'm certain it is astigmatism because like Otis said it cancels out the effect when both eyes are fusing or in my case reduces it.

Offline johnlink

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Re: Online test for astigmatism
« Reply #42 on: March 20, 2013, 05:40:04 AM »
Last night I noticed that if I view the image in http://forum.gettingstronger.org/index.php/topic,468.msg3987.html#msg3987 with my naked right (astigmatic) eye at arm's length, the vertical lines are darkest, but if I bring the image about 6 inches from my eye the vertical and horizontal lines are of equal darkness. Closer than 6 inches the horizontal lines are darkest.

If you have astigmatism, would you find out whether something similar happens to you? Before you start experimenting with the distance at which you view the image please turn the image to coincide with your axis. For example, my axis is 10 and so lines are darkest when they are 10 degrees clockwise from vertical, so I turned the image 10 degrees clockwise.

Alternatively you could view the image in http://forum.gettingstronger.org/index.php/topic,468.msg3986.html#msg3986 and notice which lines are darkest as you change the viewing distance.
« Last Edit: March 20, 2013, 06:37:51 AM by johnlink »

Offline johnlink

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Re: Online test for astigmatism
« Reply #43 on: March 20, 2013, 06:10:37 AM »
Hello John,

After 7 months of not wearing my prescription glasses I have improved my snellen from 20/60 to 20/30 but my -1.75 of astigmatism hasn't changed at all, which makes it impossible for me to see a clear image at any distance, which means I can't push print effectively. I tried the eye exercises for a few months but didn't notice a difference, I am beginning to think astigmatism is permanent.


Philipp, I'm curious if there might be a distance at which your astigmatism disappears. There is for me, as I report in this message: http://forum.gettingstronger.org/index.php/topic,468.msg4066.html#msg4066 I suspect there is such a distance for everyone with astigmatism, although I don't yet have a theoretical explanation. It might be a useful practice to push print from one side of that distance to another, observing how the darkness of the lines varies when crossing the boundary. The brain knows that the lines ought to appear the same on both sides of the boundary even though they don't appear that way, which could be an incentive for the brain to reshape the eye. I'm going to add this practice to my program.

Offline PhilippK

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Re: Online test for astigmatism
« Reply #44 on: March 20, 2013, 06:29:19 AM »
Hello John,

After 7 months of not wearing my prescription glasses I have improved my snellen from 20/60 to 20/30 but my -1.75 of astigmatism hasn't changed at all, which makes it impossible for me to see a clear image at any distance, which means I can't push print effectively. I tried the eye exercises for a few months but didn't notice a difference, I am beginning to think astigmatism is permanent.


Philipp, I'm curious if there might be a distance at which your astigmatism disappears. There is for me, as I report in this message: http://forum.gettingstronger.org/index.php/topic,468.msg4066.html#msg4066 I suspect there is such a distance for everyone with astigmatism, although I don't yet have a theoretical explanation. It might be a useful practice to push print from one side of that distance to another, observing how the darkness of the lines varies when crossing the boundary. The brain knows that the lines ought to appear the same on both sides of the boundary even though they don't appear that way, which could be an incentive for the brain to reshape the eye. I'm going to add this practice to my program.

Hi John,

Yes the vertical lines are close to equally black at about 22cm away, so that would mean that axis is -4.5 diopters. I have tried pushing print that way but it seems that would induce strain in the stronger axis.