OP
Texasguy
Contributor
I see. You are very, very smart.
I'll just leave this here, don't read it: Superior underwater vision in a human population of sea gypsies. - PubMed - NCBI
Blurry vision underwater is due to pupil dilation, which can be controlled to see as if wearing mask
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I see. You are very, very smart.
I'll just leave this here, don't read it: Superior underwater vision in a human population of sea gypsies. - PubMed - NCBI
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You are on record.
It seems that more one peer-reviewed prestigious journal article substantiates this most interesting ability. Kudos to the OP for this diversion. Fun thread, we all learned something.
Visual training improves underwater vision in children - ScienceDirect
DavBuc
Banned
This next post may be my last post of 2017, and it just might be the longest.
There are several misconceptions regarding the published study, and I will do my best to clarify for those who are less experienced in this particular subject.
The human eye has an evolutionary process that allows a person to view close up objects in such a way that they are 1) in focus and 2) single (as compared to doubled which is known as "diplopia"). The process by which nearpoint objects are focused by the human intraocular lens is known as accommodation (2 M's, most people get this wrong), and convergence (pointing the two eyes, which is performed primarily by the medial rectus muscles, one of each which attach to the globe on the nasal side of each eye. In addition, because the process of accommodation and convergence is performed by the parasympathetic nervous system (as compared to the sympathetic system (remember "fight or flight"), as a secondary function, the pupils also constrict.
Many human beings have dysfunctional accommodative/convergence systems, and vision therapy is often utilized to improve these skills, whereby an exotropic individual (one who has an outward eye turn) strengthens their convergence ability and an esotropic person (crossed eye) can learn to relax their convergence abilities, or increase the accommodative ability, and/or improve their divergence ability so as to avoid the double vision that occurs when the two eyes are not aligned upon the fixation object.
There is no question that accommodation and convergence abilities can be trained and enhanced, this is the root of vision therapy and there are few ophthalmologists or optometrists who would argue this point.
Now let's get back to the study which makes a few main points.
Following some period of training, the test subjects showed "bursts of pupillary constriction" that decreased their average pupil sizes, which were not present in the untrained subjects.
They also measured improved underwater visual acuity as compared to the untrained subjects. In addition, measureable improvements were found with their accommodation and convergence skills.
The study does NOT IN ANY WAY say that the trained subjects saw better underwater than the untrained subjects NOR does it say that they see any better BECAUSE OF MIOSIS.
A person who is used to walking around with, say 20/50 vision will demonstrate better visual acuity than a person who has always had 20/20 vision and is suddenly blurred with corrective lenses to simulate 20/50 vision, in other words a child swimming underwater without a mask will learn other ways to see objects, including whatever visual acuity method was used in the study (I couldn't find where it said HOW vision was measured which is critical).
Of COURSE the trained subjects will do better on an underwater acuity chart then untrained subjects because they have adapted and adjusted- NOT necessarily because of miotic (constricted) pupils.
Even IF it could be conclusively proven that miosis improves underwater vision, the pupillary constriction AS PER THE STUDY clearly states it is in "short bursts" only, which are averaged in with the size of the pupils during the rest of the study time, which gives test results that show a "smaller mean pupil size" in the trained subjects. As an aside, what good would that do to a diver?
I understand why some people want to jump to conclusions and say "The study proves that someone can be trained to constrict their pupils underwater and see better" but it is simply not the case. Or, if it IS the case, it has yet to be proven. The linked study does no such thing.
The study mentions "contrast sensitivity" as a possible contributing factor in many places throughout the published study but then eliminates it as a possibility in the summary towards the end.
There is some talk of "blur adaptation" which is of course what I've been referring to as the reason the trained subjects scored higher on the visual acuity test than the untrained subjects.
From the study:
Neural adaptation to visual blur has been shown to improve both contrast sensitivity and visual acuity. However, it has most likely not influenced our contrast sensitivity measurements, as Mon-Williams et al. (1998) found no effect of habituation to blur on contrast sensitivity at frequencies below 5 c/deg. It may, however, have slightly influenced visual acuity: Rosenberg et al. (2004) noticed an improvement in visual acuity in myopic subjects after only 3 h of exposure to blur. If this kind of adaptation took place in our subjects, the effect would have been rather immediate and cannot explain the improvement later on. Blur adaptation may nevertheless to some extent have reduce the need for accommodation, though only by roughly one dioptre.
Let's look at that paragraph a bit more closely because it glosses over what I think is the REAL reason for the measured visual acuity improvement in the trained children.
The study discounts the importance of this process by simply saying "it may have slightly influenced visual acuity" by 1 diopter at best- (which is something but not much), and they basis this on ONE study that blurred the subjects eyes for only 3 HOURS. Obviously the trained children had a LOT more underwater exposure than that. In that paragraph it also says something ridiculous to the effect of "if this sort of neural blur adaption was the reason for the improved vision, the effect would have been immediate and wouldn't have lasted very long". Says who? You teach a person to scuba dive without a mask and recognize objects and learn their way around, and test them a few months later, whose to say they will suddenly lose that ability? And whose to say that if it was due to "blur adaptation" the effect would have been immediate? If anything it's the other way around. Blur adaptation, learning to discern objects with reduced vision, whether above or below the water, takes some time. They certainly made no attempt to explain that silly statement further.
This study is a simple case of interpreting the data as the experimenter sees fit, simply to prove their own point and ignoring evidence to the contrary.
There are several misconceptions regarding the published study, and I will do my best to clarify for those who are less experienced in this particular subject.
The human eye has an evolutionary process that allows a person to view close up objects in such a way that they are 1) in focus and 2) single (as compared to doubled which is known as "diplopia"). The process by which nearpoint objects are focused by the human intraocular lens is known as accommodation (2 M's, most people get this wrong), and convergence (pointing the two eyes, which is performed primarily by the medial rectus muscles, one of each which attach to the globe on the nasal side of each eye. In addition, because the process of accommodation and convergence is performed by the parasympathetic nervous system (as compared to the sympathetic system (remember "fight or flight"), as a secondary function, the pupils also constrict.
Many human beings have dysfunctional accommodative/convergence systems, and vision therapy is often utilized to improve these skills, whereby an exotropic individual (one who has an outward eye turn) strengthens their convergence ability and an esotropic person (crossed eye) can learn to relax their convergence abilities, or increase the accommodative ability, and/or improve their divergence ability so as to avoid the double vision that occurs when the two eyes are not aligned upon the fixation object.
There is no question that accommodation and convergence abilities can be trained and enhanced, this is the root of vision therapy and there are few ophthalmologists or optometrists who would argue this point.
Now let's get back to the study which makes a few main points.
Following some period of training, the test subjects showed "bursts of pupillary constriction" that decreased their average pupil sizes, which were not present in the untrained subjects.
They also measured improved underwater visual acuity as compared to the untrained subjects. In addition, measureable improvements were found with their accommodation and convergence skills.
The study does NOT IN ANY WAY say that the trained subjects saw better underwater than the untrained subjects NOR does it say that they see any better BECAUSE OF MIOSIS.
A person who is used to walking around with, say 20/50 vision will demonstrate better visual acuity than a person who has always had 20/20 vision and is suddenly blurred with corrective lenses to simulate 20/50 vision, in other words a child swimming underwater without a mask will learn other ways to see objects, including whatever visual acuity method was used in the study (I couldn't find where it said HOW vision was measured which is critical).
Of COURSE the trained subjects will do better on an underwater acuity chart then untrained subjects because they have adapted and adjusted- NOT necessarily because of miotic (constricted) pupils.
Even IF it could be conclusively proven that miosis improves underwater vision, the pupillary constriction AS PER THE STUDY clearly states it is in "short bursts" only, which are averaged in with the size of the pupils during the rest of the study time, which gives test results that show a "smaller mean pupil size" in the trained subjects. As an aside, what good would that do to a diver?
I understand why some people want to jump to conclusions and say "The study proves that someone can be trained to constrict their pupils underwater and see better" but it is simply not the case. Or, if it IS the case, it has yet to be proven. The linked study does no such thing.
The study mentions "contrast sensitivity" as a possible contributing factor in many places throughout the published study but then eliminates it as a possibility in the summary towards the end.
There is some talk of "blur adaptation" which is of course what I've been referring to as the reason the trained subjects scored higher on the visual acuity test than the untrained subjects.
From the study:
Neural adaptation to visual blur has been shown to improve both contrast sensitivity and visual acuity. However, it has most likely not influenced our contrast sensitivity measurements, as Mon-Williams et al. (1998) found no effect of habituation to blur on contrast sensitivity at frequencies below 5 c/deg. It may, however, have slightly influenced visual acuity: Rosenberg et al. (2004) noticed an improvement in visual acuity in myopic subjects after only 3 h of exposure to blur. If this kind of adaptation took place in our subjects, the effect would have been rather immediate and cannot explain the improvement later on. Blur adaptation may nevertheless to some extent have reduce the need for accommodation, though only by roughly one dioptre.
Let's look at that paragraph a bit more closely because it glosses over what I think is the REAL reason for the measured visual acuity improvement in the trained children.
The study discounts the importance of this process by simply saying "it may have slightly influenced visual acuity" by 1 diopter at best- (which is something but not much), and they basis this on ONE study that blurred the subjects eyes for only 3 HOURS. Obviously the trained children had a LOT more underwater exposure than that. In that paragraph it also says something ridiculous to the effect of "if this sort of neural blur adaption was the reason for the improved vision, the effect would have been immediate and wouldn't have lasted very long". Says who? You teach a person to scuba dive without a mask and recognize objects and learn their way around, and test them a few months later, whose to say they will suddenly lose that ability? And whose to say that if it was due to "blur adaptation" the effect would have been immediate? If anything it's the other way around. Blur adaptation, learning to discern objects with reduced vision, whether above or below the water, takes some time. They certainly made no attempt to explain that silly statement further.
This study is a simple case of interpreting the data as the experimenter sees fit, simply to prove their own point and ignoring evidence to the contrary.
Last edited:
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You do understand why statistics is a core component of science, I assume?
There are more than a few researchers who will passionately defend their position beyond reasonable limits. Statistics, by common agreement, is the grand arbiter of 'right' and 'wrong'. Well, more like supportable vs. far-fetched as opposed to right or wrong. Statistics allows for progress as opposed to spinning one's wheels endlessly in the mud hoping that one's perseverance will yield a 'win'. READ those articles for content and peer-reviewed supportability.
Face it, you are wrong. There is no shame in being wrong (in science). "If we knew what we are doing, we couldn't call it research"
There are more than a few researchers who will passionately defend their position beyond reasonable limits. Statistics, by common agreement, is the grand arbiter of 'right' and 'wrong'. Well, more like supportable vs. far-fetched as opposed to right or wrong. Statistics allows for progress as opposed to spinning one's wheels endlessly in the mud hoping that one's perseverance will yield a 'win'. READ those articles for content and peer-reviewed supportability.
Face it, you are wrong. There is no shame in being wrong (in science). "If we knew what we are doing, we couldn't call it research"
DavBuc
Banned
As I have clearly explained in my post above, the statistics cited in the study do not in any way, shape or form, give any credibility whatsoever to the statement that "children can be trained to constrict their pupils, as a result of the pupillary constriction they can see better underwater".
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I can play in your world too.
DavBuc
Banned
@lowvis let me ask you a question.
If you were to wear a red coat when you go outside, and 7 of those 10 times it rains, would you conclude that people who wear red coats outdoors are more likely to get rained on?
I think you would. Because the statistics prove (to you) that you're much more likely to get wet when you wear that coat.
If you were to wear a red coat when you go outside, and 7 of those 10 times it rains, would you conclude that people who wear red coats outdoors are more likely to get rained on?
I think you would. Because the statistics prove (to you) that you're much more likely to get wet when you wear that coat.
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I have retired from a long successful career in science/engineering.
Statistics 101, day one. "Statistics never proved anything and never will." That is an easy Google search. It is my observation that you like to argue and can't stand to be shown up as being wrong.
As you have not added one whit of information to this discussion, my next move is to put you on ignore and spare the OP this nonsense.
Statistics 101, day one. "Statistics never proved anything and never will." That is an easy Google search. It is my observation that you like to argue and can't stand to be shown up as being wrong.
As you have not added one whit of information to this discussion, my next move is to put you on ignore and spare the OP this nonsense.
Actually, yes there is:
"...
Blended ("Invisible") Bifocal
Although most bifocals and trifocals have visible lines at the border of lens segments, there is a blended round-seg bifocal that has a less noticeable near segment than its regular round-seg cousin. The near seg is blended into the distance portion of the lens so that it is virtually invisible..."
Bifocals and Trifocals for Vision Over 40
SeaRat
CT-Rich
Contributor
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