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Accommodation (vertebrate eye) article. This is not a forum for general discussion of the article's subject. |
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I have taught this material to medical stduents for 30 years and I think this article will only confuse the lay person who most needs a simple, clear explanation of accommodation. Put simply, in humans, contraction of the ciliary muscle REDUCES tension on the margins of the lens allowing it to relax into a more biconvex shape changing the focal length of the lens allowing the image of the close-up object to be in focus at the level of the neural retina. —Preceding unsigned comment added by 128.143.61.114 ( talk) 21:13, 26 October 2007 (UTC) Accommodation includes a number of factors, of which relaxation into a more biconcave shape of the lens is one - but only one. Other factors include anterior movement of the lens (resulting in a shallowing of the anterior chamber), contraction (miosis) of the pupil, convergence of the eyes, and several more factors. Signed: Spencer P. Thornton, M.D. Clinical Professor of Ophthalmology University of Tennessee Health Science Center —Preceding unsigned comment added by Spencer P. Thornton ( talk • contribs) 01:32, 17 July 2008 (UTC)
Nov.7, 2014 -- As a physicist teaching some optics to BIMS majors, I wanted to teach more (than in the physics text) about accommodation by the human eye. So I found my way to this article. Unfortunately, it does not get to the point the way the "Accommodation reflex" article does, with its simple figure showing how the lens changes shape during accommodation. Moreover, the discussion of mechanism, especially of the work of Schachar, is inscrutable, largely because of its technicality and length. — Preceding unsigned comment added by 74.192.30.64 ( talk) 14:34, 7 November 2014 (UTC)
Accommodation (eye) previously redirected to Accommodation reflex. There is sufficient evidence to indicate that this article deserves to stand-alone, or even be the recipient of the redirect. First of all, given that various google searchs of "accommodation" with "lens" or "eye" reveal hits in the neighborhood of 1,200,000 to 4,250,000 whereas "accommodation reflex" gets a bit over 9,000, common usage dictates "notability" for it having its own article. Secondly, accommodation can be a voluntary process and not a reflex action. AED 08:39, 7 December 2005 (UTC)
What is the degree of support of the various theories in current mainstream ophthamology? AxelBoldt 21:08, 17 November 2006 (UTC)
do we dont get more information about theories?
I am a lay contributor, but not only does th Schachar's theory seem barking from a mechanical point of view, the attributed reference is in fact a rebuttal of the theory. If we are going to include a reference shouldn't it be to Schirars original paper? Also having tracked down various references two of which quote that Schachar's theories have no support in the profession outside his immediate group, then wouldn't it be more appropriate to leave in but play down this section:
The obvious bias on the part of the pro RAS editors leads me to worry about the info's creditability. Are there non-Schachar affiliated papers supporting his hypothesis? Also, did the numerous "in press" sources ever get published?
Colloquial use of "theory". How can there be competing theories? Surely they are competing hypotheses?
I have added a critical reference (Atchison). Strasburger ( talk) 07:26, 30 September 2018 (UTC)
Ronaldaaron (22:02, 12 July 2007) replaced the previous intro synopsis with a complete rewrite. The previous synopsis was short and specific to the main theme of this article. The new synopsis:
All in all I feel that the new intro is not an improvement. If we want to introduce the age dynamics of accommodation then this should be moved to a small linking section. TerryE 02:32, 24 July 2007 (UTC)
Hi, I did my doctoral dissertation on accommodation (I'm in a different area now), and this article doesn't reflect the subject properly. It violates both the conflict-of-interest and no-original-research rules. Essentially the article has become boilerplate from Dr. Schachar's papers. Dr. Schachar is a legitimate researcher, but his theory is by no means mainstream. I think the introduction proposed above by TerryE is a good placeholder, but that the article be rewritten to follow the standard wikipedia format, i.e. Function of Accommodation; Mechanisms of accommodation (There are at least 6 different ways to solve the focusing problem -- change lens shape, change lens distance, change retina distance, change cornea shape, etc -- and there are examples of all of them in the animal kingdom. It's fascinating.) History of accommodation research (in which Dr. Schachar will get an appropriate mention, along with Scheiner, Donders, Young, Helmholtz, Crane, Charman, etc); Neurological Aspects of Accommodation (E-W nucleus, AC/A, etc); Disorders of Accommodation (including presbyopia). Cfneveu 18:59, 25 September 2007 (UTC)
I've modified the introduction suggested above to be less anthropocentric:
Cfneveu 08:16, 1 October 2007 (UTC)
The section for Schachar seems quite biased, it reads like Schachar defending his own, questionable, hypothesis. Refer to the following papers for some decent numerical studies severely calling into question the model that Schachar based his initial claims upon:
Burd (1999): Mechanics of Accommodation of the Human Eye
Judge (2002): Modelling the Mechanics of Accommodation and Presbyopia
Burd (2002): Numerical Modelling of the Accommodating Lens.
EDIT: Sorry about the 'unsigned' just an undergraduate (not an expert) doing some related reading, seems like pretty clear bias even without expert level knowledge of the topic though. —Preceding unsigned comment added by 58.172.106.11 ( talk) 10:41, 17 May 2010 (UTC)
For now I have just flagged the article, but I do think most of the section should be removed. —Preceding unsigned comment added by 58.172.106.11 ( talk) 10:37, 17 May 2010 (UTC)
Schachar's theory has not found any support in Ophthalmology nor Vision Science. All references in that section are from the author, so it has been given undue weight ( WP:UNDUE). There are further several papers that effectively disprove that theory. I have removed the entire section to a chapter here in the talk page (below), so as to conserve it for reference. I kept the introductory paragraph, as a pointer to that theory. Strasburger ( talk) 17:28, 8 October 2015 (UTC)
(taken from the article namespace in Oct. 2015) Strasburger ( talk) 17:28, 8 October 2015 (UTC)
References
The article would be greatly improved by a (possibly small) section describing the Visceromotor Nerves that innervate the Ciliary Body and effect contraction/relaxation. While the theoretical explanations are highly valuable, the well understood Nervous aspects of Accommodation should be included (e.g. The parasympathetic nervous system innervates the ciliary body via the short ciliary fibers that arise from the ciliary ganglion and are derived from parasympathetic neurons traveling with Cranial Nerve III.) -- TwinSteel ( talk) 03:23, 8 October 2010 (UTC)
I'm a layperson with respect to the scientific understanding of accommodation but wanted to note that I believe the article is of great importance (addressing the categorization of Unknown Importance - Biology). The reason is that accommodation is one of the few remaining problems to be solved in creating practical head-mounted displays. When these devices become mainstream they will have a huge impact on our society.
Convergence -- this does not help focus the image on the retina as stated in the article, it helps to center the image over the macula and fovea, the center (densest part) of the retina. Accomodation is what focuses the image on the retina. Convergence controls the position of the image, accomodation the focus. -- I am a practicing board certified ophthalmologist in the USA. Relopez3 ( talk) 03:11, 21 September 2011 (UTC)
Proof: Covering one eye eliminates convergence, but does not prevent adaptation. Rcunning ( talk) 01:33, 26 October 2011 (UTC)
My problem with this page is the diagram of the eye optics. The eye lens is only a small part of the focussing system of the eye; most of the bending of the light entering the eye takes place at the cornea. Most eye diagrams (including the ones associated with this article) incorrectly show the light not being bent at the cornea, but being bent at the two surfaces of the lens. The refractive indices of the aqueous humour, the vitreous humour, and the eye lens itself are quite close one to another, and so the bending of light introduced by the lens is comparatively small. There is a huge difference between the refractive index of the cornea and of the surrounding air, and so that surface has the potential to introduce large changes in the direction of a ray of light. 58.173.194.6 ( talk) 22:04, 4 December 2012 (UTC)
This article seems to focus on accommodation in the human eye. However, other animals have different strategies for accommodation. For instance, some fish accommodate by adjusting the position of the lens relative to the retina, rather than changing the lens shape. Animals with compound eyes do not accommodate at all, as far as I know. The article should probably touch on this sort of thing somewhere. 138.16.21.199 ( talk) 20:59, 12 December 2012 (UTC)
I'm curious about the following:
"The young human eye can change focus from distance (infinity) to 7 cm from the eye in 350 milliseconds. This dramatic change in focal power of the eye of approximately 13 diopters (diopter is the reciprocal of focal length in meters) occurs as a consequence of a reduction in zonular tension induced by ciliary muscle contraction."
How is that 13 diopters calculated? Since 7 cm is equal to .07 meters and 1/.07 = 14.3 it seems to me that the change in focal power is just over 14 diopters, and the "13" in the quoted sentence ought to be "14". Is my reasoning correct or am I missing something? John Link ( talk) 08:04, 9 February 2013 (UTC)
You can cause double vision using eyeglasses, broken ones (with temples or earpieces off) would be best for this. Put the glasses before your eyes and look at some object. If you have good vision and the lenses are +2 or +3 dioptres, the object has to be quite near for good focus. Now move one lens up and the other down by, say, 3 mm each. One image will go up and the other down. After a second your vision will align the images back. Now question: Is the adjustment made on "software" or "hardware" level? -- Stankot ( talk) 10:39, 15 March 2016 (UTC)
I'm not sure if anyone is active on this page. If not I'll be going ahead in the near future with a revision that I think is required as it's a C class article. Firstly, for a member of the public, accommodation means a place to stay. "Focusing" of the eye has to also point to this article and if possible the word focus appear in the title. Also it currently seems to be an article only on the human lens with other vertebrates left out. While the human lens is the most studied there is plenty to include from other vertebrates, at least a summary outlining differences among vertebrates and referring within the article to fish, reptile and amphibian mechanisms. Another article on the vertebrate lens is getting quite long and the section on accommodation within it needs expanding. It would be better to expand this shorter article and refer to from that article. If there are no objections I'll go ahead with the ideas outlined here if no one else is currently interested in doing it. Tgru001 ( talk) 23:35, 18 June 2023 (UTC)
This is the
talk page for discussing improvements to the
Accommodation (vertebrate eye) article. This is not a forum for general discussion of the article's subject. |
Article policies
|
Find medical sources: Source guidelines · PubMed · Cochrane · DOAJ · Gale · OpenMD · ScienceDirect · Springer · Trip · Wiley · TWL |
![]() | This ![]() It is of interest to the following WikiProjects: | ||||||||||||||||||||||||||||||||||||
|
I have taught this material to medical stduents for 30 years and I think this article will only confuse the lay person who most needs a simple, clear explanation of accommodation. Put simply, in humans, contraction of the ciliary muscle REDUCES tension on the margins of the lens allowing it to relax into a more biconvex shape changing the focal length of the lens allowing the image of the close-up object to be in focus at the level of the neural retina. —Preceding unsigned comment added by 128.143.61.114 ( talk) 21:13, 26 October 2007 (UTC) Accommodation includes a number of factors, of which relaxation into a more biconcave shape of the lens is one - but only one. Other factors include anterior movement of the lens (resulting in a shallowing of the anterior chamber), contraction (miosis) of the pupil, convergence of the eyes, and several more factors. Signed: Spencer P. Thornton, M.D. Clinical Professor of Ophthalmology University of Tennessee Health Science Center —Preceding unsigned comment added by Spencer P. Thornton ( talk • contribs) 01:32, 17 July 2008 (UTC)
Nov.7, 2014 -- As a physicist teaching some optics to BIMS majors, I wanted to teach more (than in the physics text) about accommodation by the human eye. So I found my way to this article. Unfortunately, it does not get to the point the way the "Accommodation reflex" article does, with its simple figure showing how the lens changes shape during accommodation. Moreover, the discussion of mechanism, especially of the work of Schachar, is inscrutable, largely because of its technicality and length. — Preceding unsigned comment added by 74.192.30.64 ( talk) 14:34, 7 November 2014 (UTC)
Accommodation (eye) previously redirected to Accommodation reflex. There is sufficient evidence to indicate that this article deserves to stand-alone, or even be the recipient of the redirect. First of all, given that various google searchs of "accommodation" with "lens" or "eye" reveal hits in the neighborhood of 1,200,000 to 4,250,000 whereas "accommodation reflex" gets a bit over 9,000, common usage dictates "notability" for it having its own article. Secondly, accommodation can be a voluntary process and not a reflex action. AED 08:39, 7 December 2005 (UTC)
What is the degree of support of the various theories in current mainstream ophthamology? AxelBoldt 21:08, 17 November 2006 (UTC)
do we dont get more information about theories?
I am a lay contributor, but not only does th Schachar's theory seem barking from a mechanical point of view, the attributed reference is in fact a rebuttal of the theory. If we are going to include a reference shouldn't it be to Schirars original paper? Also having tracked down various references two of which quote that Schachar's theories have no support in the profession outside his immediate group, then wouldn't it be more appropriate to leave in but play down this section:
The obvious bias on the part of the pro RAS editors leads me to worry about the info's creditability. Are there non-Schachar affiliated papers supporting his hypothesis? Also, did the numerous "in press" sources ever get published?
Colloquial use of "theory". How can there be competing theories? Surely they are competing hypotheses?
I have added a critical reference (Atchison). Strasburger ( talk) 07:26, 30 September 2018 (UTC)
Ronaldaaron (22:02, 12 July 2007) replaced the previous intro synopsis with a complete rewrite. The previous synopsis was short and specific to the main theme of this article. The new synopsis:
All in all I feel that the new intro is not an improvement. If we want to introduce the age dynamics of accommodation then this should be moved to a small linking section. TerryE 02:32, 24 July 2007 (UTC)
Hi, I did my doctoral dissertation on accommodation (I'm in a different area now), and this article doesn't reflect the subject properly. It violates both the conflict-of-interest and no-original-research rules. Essentially the article has become boilerplate from Dr. Schachar's papers. Dr. Schachar is a legitimate researcher, but his theory is by no means mainstream. I think the introduction proposed above by TerryE is a good placeholder, but that the article be rewritten to follow the standard wikipedia format, i.e. Function of Accommodation; Mechanisms of accommodation (There are at least 6 different ways to solve the focusing problem -- change lens shape, change lens distance, change retina distance, change cornea shape, etc -- and there are examples of all of them in the animal kingdom. It's fascinating.) History of accommodation research (in which Dr. Schachar will get an appropriate mention, along with Scheiner, Donders, Young, Helmholtz, Crane, Charman, etc); Neurological Aspects of Accommodation (E-W nucleus, AC/A, etc); Disorders of Accommodation (including presbyopia). Cfneveu 18:59, 25 September 2007 (UTC)
I've modified the introduction suggested above to be less anthropocentric:
Cfneveu 08:16, 1 October 2007 (UTC)
The section for Schachar seems quite biased, it reads like Schachar defending his own, questionable, hypothesis. Refer to the following papers for some decent numerical studies severely calling into question the model that Schachar based his initial claims upon:
Burd (1999): Mechanics of Accommodation of the Human Eye
Judge (2002): Modelling the Mechanics of Accommodation and Presbyopia
Burd (2002): Numerical Modelling of the Accommodating Lens.
EDIT: Sorry about the 'unsigned' just an undergraduate (not an expert) doing some related reading, seems like pretty clear bias even without expert level knowledge of the topic though. —Preceding unsigned comment added by 58.172.106.11 ( talk) 10:41, 17 May 2010 (UTC)
For now I have just flagged the article, but I do think most of the section should be removed. —Preceding unsigned comment added by 58.172.106.11 ( talk) 10:37, 17 May 2010 (UTC)
Schachar's theory has not found any support in Ophthalmology nor Vision Science. All references in that section are from the author, so it has been given undue weight ( WP:UNDUE). There are further several papers that effectively disprove that theory. I have removed the entire section to a chapter here in the talk page (below), so as to conserve it for reference. I kept the introductory paragraph, as a pointer to that theory. Strasburger ( talk) 17:28, 8 October 2015 (UTC)
(taken from the article namespace in Oct. 2015) Strasburger ( talk) 17:28, 8 October 2015 (UTC)
References
The article would be greatly improved by a (possibly small) section describing the Visceromotor Nerves that innervate the Ciliary Body and effect contraction/relaxation. While the theoretical explanations are highly valuable, the well understood Nervous aspects of Accommodation should be included (e.g. The parasympathetic nervous system innervates the ciliary body via the short ciliary fibers that arise from the ciliary ganglion and are derived from parasympathetic neurons traveling with Cranial Nerve III.) -- TwinSteel ( talk) 03:23, 8 October 2010 (UTC)
I'm a layperson with respect to the scientific understanding of accommodation but wanted to note that I believe the article is of great importance (addressing the categorization of Unknown Importance - Biology). The reason is that accommodation is one of the few remaining problems to be solved in creating practical head-mounted displays. When these devices become mainstream they will have a huge impact on our society.
Convergence -- this does not help focus the image on the retina as stated in the article, it helps to center the image over the macula and fovea, the center (densest part) of the retina. Accomodation is what focuses the image on the retina. Convergence controls the position of the image, accomodation the focus. -- I am a practicing board certified ophthalmologist in the USA. Relopez3 ( talk) 03:11, 21 September 2011 (UTC)
Proof: Covering one eye eliminates convergence, but does not prevent adaptation. Rcunning ( talk) 01:33, 26 October 2011 (UTC)
My problem with this page is the diagram of the eye optics. The eye lens is only a small part of the focussing system of the eye; most of the bending of the light entering the eye takes place at the cornea. Most eye diagrams (including the ones associated with this article) incorrectly show the light not being bent at the cornea, but being bent at the two surfaces of the lens. The refractive indices of the aqueous humour, the vitreous humour, and the eye lens itself are quite close one to another, and so the bending of light introduced by the lens is comparatively small. There is a huge difference between the refractive index of the cornea and of the surrounding air, and so that surface has the potential to introduce large changes in the direction of a ray of light. 58.173.194.6 ( talk) 22:04, 4 December 2012 (UTC)
This article seems to focus on accommodation in the human eye. However, other animals have different strategies for accommodation. For instance, some fish accommodate by adjusting the position of the lens relative to the retina, rather than changing the lens shape. Animals with compound eyes do not accommodate at all, as far as I know. The article should probably touch on this sort of thing somewhere. 138.16.21.199 ( talk) 20:59, 12 December 2012 (UTC)
I'm curious about the following:
"The young human eye can change focus from distance (infinity) to 7 cm from the eye in 350 milliseconds. This dramatic change in focal power of the eye of approximately 13 diopters (diopter is the reciprocal of focal length in meters) occurs as a consequence of a reduction in zonular tension induced by ciliary muscle contraction."
How is that 13 diopters calculated? Since 7 cm is equal to .07 meters and 1/.07 = 14.3 it seems to me that the change in focal power is just over 14 diopters, and the "13" in the quoted sentence ought to be "14". Is my reasoning correct or am I missing something? John Link ( talk) 08:04, 9 February 2013 (UTC)
You can cause double vision using eyeglasses, broken ones (with temples or earpieces off) would be best for this. Put the glasses before your eyes and look at some object. If you have good vision and the lenses are +2 or +3 dioptres, the object has to be quite near for good focus. Now move one lens up and the other down by, say, 3 mm each. One image will go up and the other down. After a second your vision will align the images back. Now question: Is the adjustment made on "software" or "hardware" level? -- Stankot ( talk) 10:39, 15 March 2016 (UTC)
I'm not sure if anyone is active on this page. If not I'll be going ahead in the near future with a revision that I think is required as it's a C class article. Firstly, for a member of the public, accommodation means a place to stay. "Focusing" of the eye has to also point to this article and if possible the word focus appear in the title. Also it currently seems to be an article only on the human lens with other vertebrates left out. While the human lens is the most studied there is plenty to include from other vertebrates, at least a summary outlining differences among vertebrates and referring within the article to fish, reptile and amphibian mechanisms. Another article on the vertebrate lens is getting quite long and the section on accommodation within it needs expanding. It would be better to expand this shorter article and refer to from that article. If there are no objections I'll go ahead with the ideas outlined here if no one else is currently interested in doing it. Tgru001 ( talk) 23:35, 18 June 2023 (UTC)