Talk:Astigmatism (optical systems)

message: Contact lens is currently nominated to be improved on Wikipedia:Article Improvement Drive. Please support the article with your vote. --Fenice 10:51, 16 January 2006 (UTC)
thread_title: Article Improvement Drive

message: I don't know if others have noticed this, but I know I have astigmatism and the "simple eye test" didn't do anything for me.  Is this test correct?
:It is intended to be a crude version of a sunburst or clock-dial test, but isn't going to work for the vast majority of people who follow the instructions. I'm going to remove that section and add some information about those tests. -AED 17:07, 30 March 2006 (UTC)
thread_title:  Re: A simple eye test 

message: I see that the optics use of "astigmatism" has been added here. While it may not be obvious, the optics and ophthalmology uses of the term do not refer to the same effect. The ophthalmological condition is a result of a misshapen lens (or cornea). The optical aberration happens even for perfectly-formed spherical optics. These two concepts need to be split into two separate articles.--Srleffler 13:16, 30 March 2006 (UTC)
replies: text: In the context of clinical ophthalmology, "astigmatism" usually refers to the on-axis aberration. I'm not sure if the best way to address these contextual differences is to expand on them or to split the article. -AED 18:20, 30 March 2006 (UTC)
thread_title: Split

message: Actually, if astigmatism is defined as a variation of system focal length with clocking angle around the optical axis, it does mean the same thing to both optical design and opthalmics.  Centered optical systems with figure-of-revolution surfaces have no axial astigmatism, but nearly all have astigmatism away from the axis.  This includes the human eye, which does exhibit appreciable astigmatism away from the foveal area, as a raytrace of Pomerantzoff's eye model shows in ZEMAX.  Centered systems with non-figure of revolution surfaces, such as poorly made lenses or mirrors, as well as misshapen corneas, have on-axis astigmatism as well as away from the axis.
I agree that the whole classical optics section could use a major structural scrub.  As it has been written by numerous contributors, it is inherently disjointed and uncorrelated, with numerous undefined and/or un-crossreferenced terms.  
But as you say, Wikipedia is one of the best things to ever come from the Internet. —This unsigned comment was added by JonesMI (talk • contribs) .
:In the context of clinical ophthalmology, "astigmatism" usually refers to the on-axis aberration. I'm not sure if the best way to address these contextual differences is to expand on them or to split the article. -AED 18:20, 30 March 2006 (UTC)
thread_title:  Optics/Opthalmics use of astigmatism 

message: Just wondering why the ophthalmological use of "astigmatism" was chosen to be moved to Astigmatism (eye) rather than the optics use moved to Astigmatism (optics). No doubt there is overlap, but I would guess that most people searching for "astigmatism" are looking for the medical condition. -AED 05:18, 10 April 2006 (UTC)
replies: text: See above, and the new text. I'm trying to encompass both uses of the term in this article, in summary style, so this article will contain a summary or overview of ophthalmic astigmatism that particularly focuses on how it relates to the more general use of the term in optics. The new article Astigmatism (eye) would contain the technical details relevant only to those with greater interest in the medical condition. Let me know if Astigmatism (eye) is not the best name for this. I plan to fix I have fixed the links to this page as appropriate.--Srleffler 05:32, 10 April 2006 (UTC)
thread_title: Split

message: Might be good to put a selection right at the start of astigmatism, something like
* Astigmatism (eye)
* Astigmatism (optics)
I'm also working on the tangential/sagittal plane drawings, should have something by the weekend.--Mike 10:48, 11 April 2006 (UTC)
replies: text: Another approach would be to focus on the object space sagittal plane. The rays can be shown throughout the system, but one need only show (and define) a single sagittal plane. Rays that propagate in the sagittal plane in object space are sagittal rays, and remain so even in image space. We don't necessarily need to show the image space "sagittal" plane, and it might be clearer not to. The definition presently in the article considers object space only. We do need to mention in the article that the sagittal plane is not a single plane for the whole system, but changes in each optical space.--Srleffler 05:22, 12 April 2006 (UTC)
replies: text:  I agree with Srleffler. Although I get your point, I think it's clearer to just show a single sagittal plane. I think Hecht's diagram is very good, and we should try to make up one that is of the same type. --Palleas 09:35, 12 April 2006 (UTC)
thread_title: Diagrams

message: what causes astigmatism? is it genetics? can astigmatism be caused by environmental factors? is the cause unknown? can it be cured by laser treatment (not sure if that is discussed)? these questions need to be addressed.
PMoney 08:25, 19 June 2006 (UTC)
thread_title:  Causes/Origins 

message: I recently went to have my eyes checked and was told that I have astigmatism, albeit "just a little." He came to his conclusion based on a series of tests with white superimposed on green and red backgrounds. I observed the letters through a phoropter. I was asked which letters appeared clearer: the ones superimposed on the green or red background? This does not appear to be a reasonable test for astigmatism. If I am not mistaken, shouldn't an astigmatism chart be used if one was to diagnose astigmatism? Anyone have any ideas?
mezzaninelounge 05:53, 20 July 2006 (UTC)
replies: text: You might get a better answer if you posted your question over at talk:Astigmatism (eye).--Srleffler 11:04, 20 July 2006 (UTC)
thread_title: Green and Red

message: The cross example seems a bit far-fetched.  Is it confusing the image with the tracing of rays through a cross-shaped pattern on the lens?  The varying focus is not an effect of the image, unless we're talking about off-axis effects.— Preceding unsigned comment added by 192.187.147.51 (talk • contribs) 23:30, 4 January 2007 (UTC)
replies: text: If your object is a cross, and it is oriented with its legs in the major directions of the astigmatism, then its two different directions of legs will focus as two different depth.  The relevant property of the cross is its orthogonal linear features, such than blur along the linear feature will not be noticable in the image.  Like if you used a plus sign or a letter T in the little text image example.  Perhaps there's a better way to phrase it? Dicklyon 00:37, 5 January 2007 (UTC)

text: As to whether it is off-axis only or on-axis, that depends on the type of astigmatism.  In the human eye, a cylindrical error will result in on-axis astigmatism.  In most man-made optical systems, the lenses are spherical (no cylindrical error), so the astigmatism will only be off-axis. Dicklyon 00:40, 5 January 2007 (UTC)

text: See a not-so-good illustration of cross image here: . Dicklyon 01:12, 5 January 2007 (UTC)
thread_title: Focusing a cross

message: I recently went for a consultation for Laser eye corrective surgery, and was told because I have astigmatism. Laser Eye Surgery is not reccommended as it can possible make your sight worse. He said this is the case with all astigmatisms. Should this be mentioned in the main article? Randomjack 09:23, 21 February 2007 (UTC)
replies: text: Not in this article, but possibly in Astigmatism (eye) or in Refractive surgery or one of the articles on specific laser surgery procedures. The change should probably be made by someone who knows more about it, though. There are a variety of "laser eye surgery" techniques, some of which are used to correct astigmatism.--Srleffler 12:45, 21 February 2007 (UTC)
thread_title: Laser Surgery & Astigmatism

message: I came to this article, which is quite good, hoping to find out how the axis of astigmatism is interpreted from my Rx, but there was no mention of this.  MaxEnt 03:47, 23 August 2007 (UTC)
thread_title: Axis of opth astig

message: As a student Thomas Young discovered that he had problems with one eye in 1793. In the following years he was able to do research on his seeing problems. He presented his findings in an Bakerian lecture in 1801.
Independent from Young George Biddell Airy discovered the phoneme of astigmatism on his own eye. Airy presented his observations on his own eye in February 1825 at the Cambridge Philosophical Society. Airy was able to produce lenses to correct his seeing problems by 1825,  while other sources put this into 1827 when Airy obtained cylindrical lenses froom an optitian from Ipswich. The name for the condition was not given by Airy, but from William Whewell.
By the 1860s astigmatism was a well established concept in ophthalmology.
 And chapters in books describe the discovery of astigmatism.
====References====
—— Preceding unsigned comment added by Stone (talk • contribs) 12 February 2011 (UTC)
:This Ngram certainly supports the statement that books described astigmatism from the 1860s. wbm1058 (talk) 16:01, 19 October 2016 (UTC)
thread_title: History section

message: —— Preceding unsigned comment added by Stone (talk • contribs) 12 February 2011 (UTC)
:This Ngram certainly supports the statement that books described astigmatism from the 1860s. wbm1058 (talk) 16:01, 19 October 2016 (UTC)
thread_title: References

message: WHAT'S AN ASTIGAMATIC SYSTEM?  "FORM A CROSS"??? THIS IS CONFUSING FROM TEH VERY FIRST SENTENCE  — Preceding unsigned comment added by 216.183.185.133 (talk) 20:05, 16 April 2012 (UTC)
thread_title:  Untitled 

message: There is a move discussion in progress on Talk:Astigmatism (eye) which affects this page. Please participate on that page and not in this talk page section. Thank you.  —RMCD bot 06:15, 6 October 2016 (UTC)
thread_title: Move discussion in progress

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