Talk:Visual acuity

message: There are only 11 lines in the eye chart. So why not 20/1-11?
-G  — Preceding unsigned comment added by 70.27.113.62 (talk) 01:33, 2 April 2012 (UTC)
thread_title: Denominator is needlessly confusing

message: Is is possible to test your own vision at home without going to an eye doctor?  Or is special equipment needed?  It seems like all you need is a paper with letters of a certain size, the right amount of light and a measuring tape.  Perhaps some instructions on how to determine your visual acuity at home could be added.KannD86 (talk) 14:31, 28 May 2009 (UTC)
replies: text: Note that testing your distance acuity would not give you much information about the health of the eye, and nothing about the peripheral vision.  —Preceding unsigned comment added by 98.94.166.88 (talk) 22:04, 8 January 2011 (UTC)
replies: text: You could use the Freiburg Visual Acuity Test (FrAcT) at home on your computer. Strasburger (talk) 18:45, 18 January 2014 (UTC)
thread_title: testing your own vision?

message: I feel that the article has a lot more to say about visual acuity. Also it can be reorganized to structure it a little more. I will work on it in the following days if is there no objection.
:Go for it! (Please sign your user name with  ~~~~ .) AED 18:05, 22 December 2005 (UTC)
replies: text:  Ok. Didn't know how. :) Rafael Sepulveda 20:41, 23 December 2005 (UTC)
thread_title:  Remake article 

message: Do you think it is important to mention the tecnique of measuring visual acuity? Because nothing is being mentioned about that, and also nothing is being mentioned of near visual acuity and pin hole. But the article is growing a lot by now....
Rafael Sepulveda 20:45, 23 December 2005 (UTC)
replies: text: I think all of the above should eventually be added. Keep up the good work! AED 21:54, 23 December 2005 (UTC)
thread_title:  Add some things... 

message: I'm not pleased with the 'emmetropia' link to point to 'refractive error' page. Being this a complex subject (not a normal distribution graph, being that most people is lightly hyperope yet achieve 20/20, etc.) it should have it's own wikipedia page. What do you think?
:“Emmetropia” should have its own article as long as it is not merely a definition of the term (per WP:WWIN). If you want to expand the article beyond a definition, go ahead and create it. I pointed the link to refraction error because that is currently the most appropriate place to find a definition of “emmetropia”; and that definition does not state that mild hyperopia equals emmetropia. AED 05:21, 27 December 2005 (UTC)
thread_title:  emmetropia 

message: I've added a lot of things... maybe a little polishing will be needed. :) Also, near vision definition and the all the standard optotypes used have to be added. Any more things I'm missing? Rafael Sepulveda 09:40, 26 December 2005 (UTC)
replies: text: Maybe mention of Jaeger notation and peripheral vs. foveal acuities. AED 05:21, 27 December 2005 (UTC)
replies: text: Near visual acuity is being a lot difficult to find accurate, relevant information... still on the search. Rafael Sepulveda 08:53, 30 December 2005 (UTC)
replies: text: Try http://webeye.ophth.uiowa.edu/asorn/CE/2004-04Assessment.pdf and http://www.asnt.org/publications/materialseval/basics/mar07basics/mar07basics.htm for more information about Jaeger and others, including point size equivalents (and a critique that there are not more consistent standards). Kevinbsmith (talk) 13:29, 29 December 2008 (UTC)
thread_title:  A lot added by now... 

message: Do we have any references for maximum VA and/or average VA, aided or unaided, that we can include? I found one , but it doesn't state whether the students were aided or unaided. AED 05:57, 27 December 2005 (UTC)
replies: text: Maybe this?  Rafael Sepulveda 08:46, 27 December 2005 (UTC)
replies: text: I can't find anything to document that 20/12 or 20/16 is "average"? AED 00:20, 28 December 2005 (UTC)
replies: text: It's just mentioned (no reference) in Duane's V.5 Ch.51 Rafael Sepulveda 04:14, 28 December 2005 (UTC)
replies: text: I'm just a lay person.  I've been searching the web for statistics on human visual acuity and have found nothing.  You would think an article on visual acuity would have statistics on the top 1%, top 10% bottom 10% and bottom 1%, or something like that.  But all we have is 20/20 is average.  50.71.210.133 (talk) 07:11, 31 March 2013 (UTC)

text: Is 20/20 really average???  Does anyone have a study to back that up? If so, citation needed! 50.71.210.133 (talk) 07:11, 31 March 2013 (UTC)
replies: text: No, 20/20 is not average. The difficulty here is that this is age dependent. Below around 45 years of age, the average is much better; above it's lower. There are graphs in the optometry literature which make this precise. A main reason for the decline with age is increasing opacity of the lens and cataract. Recently the population statistics have changed again since cataract operations have become standard. — There should be a section on age dependence. Strasburger (talk) 19:01, 18 January 2014 (UTC)
thread_title: Maximum VA vs. average VA

message: A lot of the statements in the History section appears verbatim in Duane's. Can you rewrite or paraphrase some of these statements so we don't violate WP:COPY? Thanks! AED 00:20, 28 December 2005 (UTC)
replies: text: Working on it. Rafael Sepulveda 04:15, 28 December 2005 (UTC)
thread_title: Duane's

message: the maximum acuity of the human eye without visual aids (such as binoculars) is generally thought to be around 20/15 (6/4.5)
the average visual acuity of healthy eyes is 20/16 or 20/12
I don't know much about visual acuity, but one of these (maybe both, of course) is almost certainly false.
:Depending on the studies made by different authors, it can be one or another (or even something else!). They're both approximate values and can't be stated precisely. Rsepulveda 08:52, 15 February 2006 (UTC)
replies: text: Well, imo they could be stated more precisely but more detail is required then. E.g., binocular acuity is much better than monocular acuity, and acuity depends heavily on luminance. Strasburger (talk) 19:07, 18 January 2014 (UTC)
thread_title: Contradiction

message: As many people are aware, a traditional test of visual acuity is the abilty to distinguish Mizar from Alcor, two stars in the big dipper. Given that the angle that separates them is about 12 minutes, what is the minimum visual acuity necessary to distinguish them (in terms of 20/x)? I was thinking about adding this to the Mizar article to quantify this "good vision" folktale once and for all. (Granted, it could be considered original research, but if it's only the result of some formula, it's probably not that bad, and I also really want to know.)
71.102.186.234 10:54, 26 November 2006 (UTC)
replies: text: A 20/20 vision is defined as being able to discern the letters on the Snellen chart when they are 5 arc minutes at 480 lx illumination. Given the rather small differences between the P and F I'd say it's equivalent to discerning two point sources at 2 minutes. Then 12 minutes would be equivalent to 1/6th of 20/20, i.e. 3/20. However, the night sky is much much darker than 480 lx, such that you can't really compare these two measures. Han-Kwang 11:25, 26 November 2006 (UTC)

text: I think you make your point clear. My understanding is that in maths you should always be very careful about using ratios to zero. Refer to 20:40 or 20:10 but not 20:0. You're right that 20:0 is nonsense. That's just comparing something with nothing.  —Preceding unsigned comment added by 83.67.127.181 (talk) 23:47, 27 April 2008 (UTC)
thread_title:  Star vision test 

message: OK, so I was reading Mad Magazine (specifically the Monroe section), and I run into this part where a man using a magnifying glass says "Damn 10/10 vision!" But wouldn't this be like saying "Damn 20/20 vision" or "Damn 20/18 vision"??????? What is 10/10 vision?????? 131.191.64.130 (talk) 02:59, 30 November 2007 (UTC)
replies: text: 10/10 vision would be the same as 6/6 vision or 20/20 vision.  For visual acuity of A/B, you can see at distance A what a normal person can see at distance B.  — Preceding unsigned comment added by 50.71.210.133 (talk) 07:29, 31 March 2013 (UTC)
thread_title:  10/10 vision bad?????? 

message: I'd disagree, based on my experience in an ophthalmology department, that the LogMar isn't used clinically. It's about 50/50 LogMar/Snellen now. Also, it doesn't just refer to a different way of expressing Snellen measurements, but a LogMar chart is also a completely different way. Should I add this into the article? Andrew Jacklin 15:47, 4 December 2007 (UTC)
replies: text: I'd agree. Also, there is very little information about LogMAR on wikipedia. Could someone increase it a bit, maybe add a new page to talk about it? Snellen chart exists, so why not LogMAR chart? Also, it is not referred to as a Bailie-Lovie chart - the guys who invented the LogMAR chart  Ged3000 (talk) 19:20, 19 May 2008 (UTC)
replies: text: As an extra - if someone is able to make those changes, the simulation chart at this website might be a useful link... Ged3000 (talk) 19:31, 19 May 2008 (UTC)
thread_title:  LogMar 

message: In the table of visual acuity scales, shouldn't the decimal corresponding to 20/30 and 6/9 be 0.67, rather than 0.63? -- Sakurambo 桜ん坊 12:23, 7 July 2008 (UTC)
replies: text: Yes, it should. Now fixed. Isidore (talk) 19:02, 29 December 2009 (UTC)
thread_title:  Visual acuity scales 

message: "the sensitivity of the interpretative faculty of the brain" is an early phrase in the summary.  Processing appears to happen in the retina, whence signals are propagated to thebrain not depending on just one photoreceptor, but on several.  "brain" should perhaps be changed to something including more of the nervous(?) system from retina to optic and other cortex.  Or removing "of the brain" and discussing later where the interpretative faculty is implemented. This is an articlet hat looks good, and is going to be useful and interesting to many people. Midgley (talk) 08:27, 14 May 2009 (UTC)
thread_title:  Where processing happens 

message: I think it would be more clear to say "the first number" and "the second number", since fractions aren't quite universal.  —Preceding unsigned comment added by Sam Coskey (talk • contribs) 02:03, 3 March 2010 (UTC)
thread_title:  numerator / denominator 

message: The article says that 20/10 is "superior", i.e. you can see at 20 feet what others can only see at 10. But isn't that merely hyperopia, farsightedness?? Doesn't that mean that if you have 20/10, you see worse up close, say 1/2?--Dbjorck (talk) 09:00, 12 September 2010 (UTC)
replies: text: No, not necessarily. In the past, my father had 28/20 and he doesn't suffer for any hyperopia or presbyopia. Birds, for example, generally have a superior acuity (I think, 140/20 for certain species), and non any linked problems. (sorry if I'm not clear, I have a medium level in english). Idlem (talk) 16:46, 9 July 2011 (UTC)
replies: text: No, not at all. Acuity and near/far-sightedness are different concepts and are unrelated. Strasburger (talk) 20:47, 18 January 2014 (UTC)
thread_title:  Superior vision 

message: The statement "because it does not specify the nature of the problem with the lens" I think refers to the ability of all parts of the visual system, not just the crystalline lens.  —Preceding unsigned comment added by 98.94.166.88 (talk) 22:18, 8 January 2011 (UTC)
thread_title:  used "lens" meaning "eyes"? 

message: "The denominator indicates the size of the letters"  I believe this statement is incorrect. How does the number 20 indicate the size of the letters?  — Preceding unsigned comment added by 71.249.250.64 (talk) 17:33, 18 August 2011 (UTC)
thread_title:  Denominator in the phrase 20/20 

message: This article states that "20-20 is perfect vision" in the Physiology of visual acuity section. Later, in the Normal vision section, it states that "it is inaccurate to refer to 20/20 visual acuity as 'perfect' vision". I imagine that the latter is correct and that the former should be changed, but I don't really know much on this topic so I'll leave it for somebody else to change.  — Preceding unsigned comment added by 27.32.110.51 (talk) 05:35, 16 February 2012 (UTC)
thread_title:  Perfect vision 

message: The author states "In the expression, 20/20 vision, the numerator refers to the distance in feet between the subject and the chart. The denominator indicates the size of the letters, expressed in millimeters. The denominator does not measure the height of the letters. Rather, the denominator measures the distance of the separation of the lines that make up those letters."
 
then goes on to state-
"At 20 feet or 6 metres, a human eye with nominal performance is able to separate lines that are one arc minute apart (equivalent to lines that are spaced 1.75 mm apart."
How does the denominator ( the number 20) in the term 20/20 represent 1.75 millimeters?  
I believe the latter statement "A visual acuity of 20/20 is frequently described as meaning that a person can see detail from 20 feet (6.1 m) away the same as a person with normal eyesight would see from 20 feet." to be true.  — Preceding unsigned comment added by 71.249.250.64 (talk) 22:28, 1 March 2012 (UTC)
thread_title:  Denominator in the phrase 20/20 

message: There is something inconsistent in the introduction.  Paragraph 6 says "The letters in the lowest line in the Snellen chart are composed of lines that are separated by a visual angle of one arc minute".  In the figure of the Snellen chart, the lowest line is three lines below the 20/20 line.  So if you can discern lines separated by one arc minute you are seeing much better than 20/20.
The next paragraph says " a human eye with nominal performance is able to separate lines that are one arc minute apart" so, nominal must be a lot better than 20/20.  Then the next sentence says "A vision of 20/20 is considered nominal".  
So, either normal human acuity can resolve 1 arc minute and the lowest line on the Snellen chart has features much less than 1 arc minute, or the lowest line on the Snellen chart has 1 arc minute features and 20/20 human has much less resolution than 1 arc minute. Constant314 (talk) 02:15, 11 December 2012 (UTC)
thread_title:  Inconsistent definition of 20/20 vision 

message: How can the visual acuity in hawks be 20/2? Considering 20/20 is 60 seconds of arc and implies a 2.3mm diffraction limited aperture using the Rayleigh criterion then a 20/2 acuity implies a diffraction-limited aperture of around 23mm, for a 6 seconds of arc resolution. That's far bigger than even owl's eyes... impossible! Even yesterday I was looking at an eagle and her eyes don't have a much bigger pupil in the sun than ours, which are already near diffraction-limited. And her eyes are relatively small also, and therefore her pupil can't grow above 6 or 7mm at most, limiting acuity at best to 20/7 or so.  — Preceding unsigned comment added by Rnbc (talk • contribs) 21:02, 21 July 2013 (UTC)
replies: text: Raptors do have other adaptations within their eyes that are absent on humans, such as strategically placed oil droplets within their eyes that increase the contrast. Also I don't know where you are getting the 20/2 visual acuity for hawks. They don't really get much better than 20/7.5, as you predicted. Humans have ‘foveal vision’ (acute only in the center), while raptors, on the other hand, have a high proportion of cone cells spread over the entire retina. This provides raptors with an all-around visual awareness far superior to that of humans. Raptors are also sensitive to a larger color spectrum than humans are. They have two types of cone cells (we have only one), four or five color-sensitive pigments (we have just three), and oil droplets which enhance contrast in different parts of the field of vision.  — Preceding unsigned comment added by 70.208.132.194 (talk) 08:23, 19 February 2014 (UTC)
replies: text:  That's very interesting and some of it might go in the article imo (in a separate section). The "20/2" appears in a somewhat dubious reference in the section "Expression". Strasburger (talk) 10:42, 28 May 2014 (UTC)
replies: text:  The reference to 20/2 vision has now been removed, so this comment in the talk section is now historical only. Rnbc (talk) 13:20, 29 August 2014 (UTC)
thread_title:  Visual acuity in animals 

message: Someone has changed a bunch of word to 'megaman'...? a quick look at the history shows the first instance is 'brain' > 'Megaman'  — Preceding unsigned comment added by 143.65.196.20 (talk) 16:14, 31 October 2013 (UTC)
thread_title:  Megaman? 

message: I am not an expert in this field, but while reading through the article the following caught my eye:
RE: Section 5.1, Legal Definitions, near the bottom of the section it gives this example of notation used in the documentation of visual acuity:
"So, distant visual acuity of 6/10 and 6/8 with pinhole in the right eye will be: DscOD 6/20 PH 6/8. Distant visual acuity of count fingers and 6/17 with pinhole in the left eye will be: DscOS CF PH 16/17."
Is it correct to write:
DscOD 6/20 PH 6/8   --   why is it not 6/10?
and the second:
DscOS CF PH 16/17   --   why is it not 6/17?
If these notations are not a typo, and are correct as written, then it would seem an entry discussing how these numbers are derived from the raw data should be included.
Static1st (talk) 13:39, 11 August 2015 (UTC)
replies: text: There is far more wrong with the quoted passage than merely a possible typographical error. What does the phrase "Distant visual acuity of count fingers" even mean? And how could a layperson be expected to parse it? This article is full of such language. rowley (talk) 17:59, 11 December 2018 (UTC)
thread_title:  Possible Typographical Errors 

message: Just want an answer.  — Preceding unsigned comment added by 219.89.176.175 (talk) 05:22, 19 November 2015 (UTC)
replies: text: Hi. If you refer to the "multiple issues" warning, that was inserted quite some time ago (before I came here) and much of it has probably been resolved. The section "Physiology" still needs a brush-up (I did only the first paragraph). Whether it is still confusing overall I cannot say. Strasburger (talk) 15:18, 19 November 2015 (UTC)
replies: text: I have now cleaned up the section "Physiology" and removed the warning. Strasburger (talk) 13:44, 9 May 2016 (UTC)
thread_title:  Why is this entry being questioned? 

message: This article is so technical and full of jargon that an educated laymen cannot understand it. I have a degree in Computer Science from Cambridge University and am relatively technical in my general knowledge. Yet this article is beyond my ability to understand. This suggests most of the population will be unable to understand it. This article needs considerable clarification and explanation of the terms used.
:I have changed three sentences in the introduction, so at least the introduction should now (hopefully?) be straightforward to read. I might be the wrong person to tell, though, so please be more specific in where you think it needs being simpler. Strasburger (talk) 22:27, 29 August 2016 (UTC)
replies: text: I agree about the article being, overall, too technical, i.e., so concerned with using "correct" terms that it fails to inform. If, after reading a Wikipedia article, a reader has to do a general google search in order to find out what he or she came looking for, then the Wikipedia article has failed its primary function. rowley (talk) 17:52, 11 December 2018 (UTC)
thread_title:  Too technical 

message: -is this worthy of inclusion 
is procedure responses come to my talk page-thank you 
 https://en.wikipedia.org/wiki/File:Single_letter_relative_sizes_visual_acuity_measurement.jpg 
PG D'Arcy (talk) 14:49, 25 July 2018 (UTC)
thread_title:  visual acuity suggested infographic 

message: The graph in the Physiology section is slightly misleading in that the acuity beyond 40° eccentricity is too low. It looks like it goes to zero when in fact it should remain at about 5%. The graph is taken from Hunziker, 2006. I will need to look for a more accurate graph. Strasburger (talk) 15:59, 19 January 2020 (UTC)
thread_title:  Peripheral acuity too low