Author Topic: Why are some people able to see further than the 20/20 line?  (Read 7372 times)

Offline chris1213

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I started this topic with a question and unfortunately I don't have an answer. I would like someone to share some knowledge.

I understand that an eye that has grown longer is myopic because the image of a distant object will fall in front of the retina which is why we can't see from far away. I guess the longer the eye the lower the acuity. Now, an emmetropic eye will normally have an acuity of 20/20 but then why are some people able to see further than the 20/20 line. Is the eye shorter than normal or is the brain able to decipher more letters? What's the reason?

If anyone has an answer you're welcomed to reply.

Offline Todd Becker

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Re: Why are some people able to see further than the 20/20 line?
« Reply #1 on: July 18, 2013, 07:29:36 PM »
Chris,

It's an excellent question you ask, but the answer is not simple.  As this Wikipedia article makes evident, visual acuity is influenced by many factors; some "external" like distance lighting conditions, and others "internal" or physiological like the shape of the and the resolving power and density of cones in the fovea.  There is no single way to measure visual acuity -- Snellen score only addresses part of the story:

http://en.wikipedia.org/wiki/Visual_acuity

Todd

Offline Hillyman

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Re: Why are some people able to see further than the 20/20 line?
« Reply #2 on: July 18, 2013, 07:33:23 PM »
20/20 is a measure of the acuity of normal vision, acuity being the resolution of detail that the eye can see when the light is perfectly focused on the retina. Once you have the light focusing correctly on the retina (whether in the emmetropic eye or if you have corrective lenses), how much further you can see below the 20/20 line depends on how densely the rods and cones in your retina are packed. If they are more dense than "normal," then you would be able to see 20/15 and even 20/10. I can read about 20/17, with glasses (-5.5 myopia).
« Last Edit: July 18, 2013, 07:36:28 PM by Hillyman »

Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #3 on: July 18, 2013, 07:35:41 PM »
Dear Chris,

Subject: Extremely perfect vision.

Reference:  Even some normal eyes are lucky to read the 20/25 line.

When the Snellen was set up - they just used a minus lens to determine - "Best Visual Acuity".  For all practical purposes - this means the ultimate resolving power of a large number of eyes.  This is STATICIAL in nature.  Some eyes can do better than 1 minute-of-angle (so-called 20/20) and some can not.  When you are young, natural eyes with a "positive" refractive state - can see (in many cases) SLIGHTLY better than the 20/20 line.

I would strongly suggest that no one can measure "length" very accurately.  When is measure is a refractive STATE, using a trial lens kit and a Snellen - and then BY THEORY, a "length" IS CALCUATED.  (This is why I object to describing a "length" - when it can not be measured correctly.  But you certainly can measure a refractive state - yourself - and I mean objectively.)

If you do your measurement correctly, then there is a relationship between a positive refractive state - and very clear distant vision.  With a negative state, you will have difficulty reading the 20/60 line.  I think we ALL agree on that point.

If you are negative as stated, you can use a minus lens, and determine if a minus clears the 20/20 line.  I think for you, it would be a -1.0 diopter lens.  It is also possible, with your own trial-lens test - for you to read the 20/18 and perhaps the 20/15 line. 

It is my thesis, that you can get the refractive STATE of the natural eye to change by the amount of +1.0 diopters - by wearing a plus for all close work, and that very slowly, you can get that change of +1.0 diopters - even though I know it will take about a year to do it.

If you wish to translate a refractive STATE to a "length", then yes, a "shorter" eye will have the better vision.  My refractive STATE is positive (self-measured), and I have the best retina vision possible - including night vision.

Probably many people will not "like" this explanation - and that is OK.  But that is how I present the concept.

Otis




I started this topic with a question and unfortunately I don't have an answer. I would like someone to share some knowledge.

I understand that an eye that has grown longer is myopic because the image of a distant object will fall in front of the retina which is why we can't see from far away. I guess the longer the eye the lower the acuity. Now, an emmetropic eye will normally have an acuity of 20/20 but then why are some people able to see further than the 20/20 line. Is the eye shorter than normal or is the brain able to decipher more letters? What's the reason?

If anyone has an answer you're welcomed to reply.

Offline chris1213

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Re: Why are some people able to see further than the 20/20 line?
« Reply #4 on: July 18, 2013, 11:44:47 PM »
Thank you all for replying. I never thought eyesight would become such an interesting topic for me even though I used to wear what we call "eye crutches" all the time ha. Well I've been enjoying the journey of reversing my myopia, being able to sleep whenever and wherever I want without having to remember to take off the contacts, being able to focus on things with my own eyes, learning about visual acuity. It's nice.

I really appreciate Todd for writing the article for free and Otis for having so much information on the topic.

Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #5 on: July 19, 2013, 04:12:37 AM »
Hi Chirs -
I truly KNOW how difficult prevention is.  It is highly intellectual and "judgmental" on the part of the person himself.  You are VERY LUCKY, to have taught yourself how to go from 20/200, to a reasonable 20/40 to 20/60.  That allows you to pass SOME DMV tests.  The fact that you were at 20/200 - suggests that it will take some time to make "good" on that last diopter.  Personally, I *NEVER* know what you, or anyone else might do.

If it were *me*, and I was able to do almost everything with no minus on my face - I would be very happy.  I would also agree to continue to wear a plus  at the just-blur point.  I would be prepared to accept the fact that I would probably see no further "Snellen results" for about six months.

I bear no "ill-will" against any "medical person".  That is why I measure a "refractive STATE", not a "error".  The choice of words, and semantics is critical to understand these issues.  If I were "sitting in an office" - you would probably get a -2.0 diopters from me as a "prescription".  You would get this - because *ME* in my office have no "time" for you.

But when you read your Snellen, you KNOW where you stand.  I will develop a video on this topic, reviewing the "intelligent person" at 20/60, and the "office response", versus, having the insight and MOTIVATION, to 1) Keep wearing the plus for the next nine months - even if you are stalled out in a "plateau".  2) Get your own -1.0 diopter from Zennioptical for $10, and keep it in your car - until you exceed the 20/40 line on your brightly-lit Snellen.  3) Accept that this is a long-term commitment.

I am still amaized that you managed to get from 20/200 to 20/50.  I don't know *you*.  I don't know your interests.  I don't know your motivations.  But I do know that you understand that no one in *medicine* can help you.  So, you must do this yourself.

Otis


Thank you all for replying. I never thought eyesight would become such an interesting topic for me even though I used to wear what we call "eye crutches" all the time ha. Well I've been enjoying the journey of reversing my myopia, being able to sleep whenever and wherever I want without having to remember to take off the contacts, being able to focus on things with my own eyes, learning about visual acuity. It's nice.

I really appreciate Todd for writing the article for free and Otis for having so much information on the topic.

Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #6 on: July 19, 2013, 09:55:32 AM »
Subject:  Why an OD has no time for true-prevention.

Reference: Learn from people who have done it correctly - like Todd and others.

Here is how *I* check my refractive state - to avoid "judgment conflict" with an OD in his office.

http://www.youtube.com/watch?v=9OUw5YkrNWw&feature=youtu.be

I have deep respect for medical people.  But this video is about "doing prevention yourself".  I can only help by *suggesting* the need to do what this video suggests.

It the final analysis - it is your choice.

Offline chris1213

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Re: Why are some people able to see further than the 20/20 line?
« Reply #7 on: July 19, 2013, 07:57:47 PM »
Hey Otis thanks for the encouragement. I've watched your videos, and there's something I haven't done but I will. Every time I checked my Snellen I wouldn't put a direct light on it, I would just turn on my room's (full spectrum) light. After watching your videos I realized I have to buy a bulb to put it in a lamp and point the light towards the Snellen. Hope this helps me be more accurate with my readings.

Besides that, I have a question. I'm about to start college next month and I was wondering that in case I'm not able to see the board that well is it alright if a buy a lower power lens to see it? I ask because I'm concerned it will affect my vision if the room is not that big. I was thinking of either using a lower power lens and siting further from the board as much I can or use no lenses and sit the closest I can to the board when a seat is available.

Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #8 on: July 20, 2013, 03:05:58 AM »
Hi Chris -

Subject:  A consistent Snellen - for repeatable results.

You are correct.  I put a bright light on my Snellen for consistent results.  That way if I see any change, I trust my results.  I found this out when I started checking myself - this is so that we can compare results.

I am pleased you state you are going to college.  That is good, but you must be aware of one additional issue - that few take the time to understand.  This is now a "universal truth" - for those who take it seriously. 

For each year a student is in college, (all normal or natural eyes) his refraction goes DOWN by 1/3 diopter.  [Very few people take the time to understand these objective facts - but that is a large part of understanding the need for prevention.]

I don't know if this will convince you to continue to wear the plus - but it would convince me of the necessity of doing it.  Plus-prevention is not easy - it is hard for exactly that reason.  You are lucky you  are in the range of 20/60 to 20/40 (about -1.0 diopters - if you checked with that lens and Snellen.  You are also lucky you got "back" from 20/200.

OBTAINING A "WEAK" MINUS LENS - TO GIVE YOU 20/20 - ONLY WHEN NECESSARY:  This part is critical.  You can't "negotiate" any lens from an OD.  They will refuse to understand what you are doing - and why you are doing it.  They will always, "pooh pooh", the concept that you must do this yourself. 

With your "current status", you will temporarily need a minus to drive a car.  But I am still recommending you wear the plus 2.0 as long as you are in a "school environment".  Obviously, I argue for "intelligent, and low-cost EMPOWERMENT".  Today, you can obtain your own "minus glasses" from Zennioptical for about $20.  The reason for that is that you can all your own checking. 

I think with this work, you will exceed the 20/40 line in due course - and eventually get to the 20/30 to 20/15 line.  (The human eye does vary in that manner - with a well lit Snellen.   Once you get to that point, you will not need the minus in class.   You can then make your own choice about wearing it.  Remember Shadowfoot?  He was concerned when he was 20/30 - so he just made the commitment to "wear the plus" until he exceeded the 20/20 line.  I like science, and I like to be "empowered" with new concepts and methods.  I like to be doing this work - including to fortitude to obtain my own "test lenses" as I continue to "work" my way back to reasonable 20/30 to 20/15.  I will post how *I* obtain my "test" and personal lenses from Zenioptical.

Otis


Hey Otis thanks for the encouragement. I've watched your videos, and there's something I haven't done but I will. Every time I checked my Snellen I wouldn't put a direct light on it, I would just turn on my room's (full spectrum) light. After watching your videos I realized I have to buy a bulb to put it in a lamp and point the light towards the Snellen. Hope this helps me be more accurate with my readings.

Besides that, I have a question. I'm about to start college next month and I was wondering that in case I'm not able to see the board that well is it alright if a buy a lower power lens to see it? I ask because I'm concerned it will affect my vision if the room is not that big. I was thinking of either using a lower power lens and siting further from the board as much I can or use no lenses and sit the closest I can to the board when a seat is available.

Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #9 on: July 20, 2013, 09:13:48 AM »
Chris -

I like to keep things as simple and clear as possible.  Here is how you measure your PD.

http://www.youtube.com/watch?v=Wgr1wO-9Fpo

Once you have that, you can order a set of -1.0 diopter (spherical) glasses from Zennioptica - for about $11.  That's $7 and $4 shipping.  It is worth it just to proven that you can do it - when necessary.  This is very valuable for  your own crucial checking.  I will provide the site, and a short video on how to order in the next post.


Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #10 on: July 20, 2013, 09:22:44 AM »
Chris -

I believe in being in "control" of my life - if at all possible.  That includes getting my own lenses from Zennioptical.  It is more than just getting lenses.  You will be using them to judge your refractive state, using your own Snellen.  I think a simple -1.0 diopter lens will give you 20/20 on that Snellen.   Here is the Zenni site:

http://www.zennioptical.com/?option=com_fireboard

Just click through it with your PD (60 mm) and fill in the  -1.0 diopter order.  Select the frames as they show how to do it.  Here is my short video - just to get you comfortable on how *I* do it.

http://www.youtube.com/watch?v=cQVZqddnQCg

I think of it this way, "... a journey of 1,000 miles, begins with but a single step."  This is a process you can use to protect your distant vision though four years of college.  Others have done it - you should be able to do it also.   Your naked-eye distant vision is worth it.  But it does take long-term judgment and persistence.

Otis



Offline chris1213

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Re: Why are some people able to see further than the 20/20 line?
« Reply #11 on: July 20, 2013, 12:56:03 PM »
Thank you Otis for sharing your opinion and recommendations with me. I have read that you've posted several times about how vision deteriorates by 1/3 for each college year. I believe you're right because that was approximately how my vision went down each year of high school since I got my glasses. It was a little bit more stable though because I would refuse to wear them most of time even if that implied that I couldn't see the board that well. I would just copy whatever my friends wrote on their notebooks ha. It was alright until I got contacts which worsened my vision a lot and I think my eyes even became kind of allergic to them cause I would have red eyes most of the time. I also think that another reason might be the over accommodation that might have been stressing my eyes a lot and made them red.

I have bought some lenses from zennioptical and the -1 one gives me a little bit more than 20/20 vision. I just wear the -0.5 whenever I drive since it gives me about 20/30 to 20/40. I might need to use those in college in case I don't see the board but definitely I want to keep using the plus and preserving my vision.

I found interesting that I was talking to a friend who studies law and he told me, without knowing anything about the plus lens method, that whenever his vision gets tired after reading too much he puts some reading glasses and they get relaxed. I think that's a great way of preventing myopia and, in my case, reversing it.

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I must tell you something that is happening. I wrote on some posts before that I feel some kind of stiffness in my eyes when I wake up. It feels like some muscles are shaking and pushing from behind when I blink a little bit harder. I figured out that maybe I was overworking my eyes and didn't give them time to recover and rest. So yesterday I tried not to use my plus lens glasses and tried out some Bates method exercises. Today I woke up and for some good 15 minutes I was able to read the 20/25 line.

It has happened more than once that I wake up and I am able to see clearly. I go outside and take a walk to keep looking into the distance but when I come back home I can just make the 20/40 - 20/50 again. I'm not sure what I'm doing wrong so I have to keep experimenting. If anyone has experienced this or might think of any ideas about the reason for this share your opinion, I take every single opinion and recommendation into account.

Chris

Offline chris1213

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Re: Why are some people able to see further than the 20/20 line?
« Reply #12 on: July 20, 2013, 02:59:46 PM »
Otis, I am specifically writing to you. Besides what I wrote above and my question, which I'm still wondering about. I went today to Home Depot and bought a bulb for a lamp that I have. I followed the advice on your video to put the light directly on the Snellenn chart. I am glad to tell you that I make the 20/40 and the 20/30 line. Now I wonder if that's the reason I feel like outside I have better vision, the lighting makes all the difference.

Anyways, thanks for the video, it helped me.

Offline OtisBrown

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Re: Why are some people able to see further than the 20/20 line?
« Reply #13 on: July 20, 2013, 04:18:19 PM »
Hi Chris -

[Remark:  I typed a long reply - and then lost it.]

Let me continue with my remark.  I truly wondered if anyone would "get the idea", and re-start the wearing of the plus - through high school, college, and beyond.  I was very specific with Keith, about the plus NOT BEING A SHORT TERM SOLUTION.  The reason,  is that steady -1/2 diopter per year.  He started this in high school, since the age of 13, and continued, when necessary, when he saw his vision go-down, as a totally normal development. 

He then just re-started wearing the plus, yet again.  Here is his statement for your interest.

http://myopiafree.i-see.org/keitheye.txt

Note that Keith measures 20/15, which is excellent. Keith is a runner, and an athlete.  I have no doubt but that this is part of his success.  The point is that he "beat" that -1/2 diopter per year, but "recovering" vision with the plus, and simply knew it was both wise and necessary.

I will respond to your questions in due course.  I certainly believe you understand that you can do it, and accomplish what Keith did, if you have his understating and resolve to do it - when necessary.  Your checking with that "Bright Snellen" will objectively tell you when to restart - after you get to 20/20 on that chart.


Otis, I am specifically writing to you. Besides what I wrote above and my question, which I'm still wondering about. I went today to Home Depot and bought a bulb for a lamp that I have. I followed the advice on your video to put the light directly on the Snellenn chart. I am glad to tell you that I make the 20/40 and the 20/30 line. Now I wonder if that's the reason I feel like outside I have better vision, the lighting makes all the difference.

Anyways, thanks for the video, it helped me.

Offline chris1213

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Re: Why are some people able to see further than the 20/20 line?
« Reply #14 on: July 21, 2013, 11:06:15 AM »
Thank you again for the reply and encouragement Otis. I will keep wearing the plus and doing anything I can to reverse this myopia. I'll try to incorporate bates' resting methods with the plus. When I see any different results I'll keep you updated and if any other question appears on the way I'll be glad to post about it and discuss, I think this also helps future readers to have a wider view of the plus lens method.

Chris