Editing Sunglasses (section)

== Functions ==
[[File:Animation polariseur.gif|thumb|right|Effect of pair of polarized filters]]

=== Visual clarity and comfort ===
Sunglasses can improve visual comfort and visual clarity by protecting the eye from [[Glare (vision)|glare]].<ref name="Sakamoto">{{cite journal | last1 = Sakamoto | first1 = Y. | last2 = Sasaki | first2 = K. | last3 = Kojima | first3 = M. | last4 = Sasaki | first4 = H. | last5 = Sakamoto | first5 = A. | last6 = Sakai | first6 = M. | last7 = Tatami | first7 = A. | year = 2002 | title = The effects of protective eyewear on hair and crystalline lens transparency | journal = Dev Ophthalmol | volume = 35 | pages = 93–103 | doi = 10.1159/000060813 | pmid = 12061282 }}</ref>

The lenses of [[polarized sunglasses]] reduce glare reflected at some angles off shiny non-metallic surfaces, such as water. They allow wearers to see into water when only surface glare would otherwise be seen, and eliminate glare from a road surface when driving into the sun.<ref>{{Cite web | url=https://www.glasses.com/gl-us/glossary/polarized-lenses#:~:text=Polarized%20lenses%20are%20a%20type,effect%20of%20glare%20when%20outdoors| title=Glossary of Eye Definitions and Glasses Terms | website=www.glasses.com}}</ref>

=== Protection ===
[[File:DSCF1041-Mazzeo-Taormina-Italy-Castielli CC0 glasses.jpg|thumb|left|Broad temple arms protect against "stray light" entering from the sides.]]
Sunglasses offer protection against excessive exposure to light, including its visible and invisible components.

The most widespread protection is against ultraviolet radiation, which can cause short-term and long-term ocular problems such as [[photokeratitis]] (snow blindness), [[cataract]]s, [[Pterygium (conjunctiva)|pterygium]], and various forms of [[Ocular oncology|eye cancer]].<ref name="CCA">{{cite web|url=http://www.cancer.org.au/File/PolicyPublications/PSeye%20protectionAUG06.pdf|title=Cancer Council Australia; Centre for Eye Research Australia: Position Statement: Eye Protection. August 2006|access-date=2010-05-13|url-status=live|archive-url=https://web.archive.org/web/20110706124649/http://www.cancer.org.au/File/PolicyPublications/PSeye%20protectionAUG06.pdf|archive-date=2011-07-06}}</ref> Medical experts advise the public on the importance of wearing sunglasses to protect the eyes from UV;<ref name="CCA" /> for adequate protection, experts recommend sunglasses that reflect or filter out 99% or more of [[Ultraviolet type|UVA]] and [[Ultraviolet type|UVB]] light, with wavelengths up to 400&nbsp;[[nanometer|nm]]. Sunglasses that meet this requirement are often labeled as "UV400". This is slightly more protection than the widely used standard of the European Union (see [[#Standards for sunglasses|below]]), which requires that 95% of the radiation up to only 380&nbsp;nm must be reflected or filtered out.<ref name="Huenig">[https://cocoleni.de/content/wp-content/uploads/2018/11/makulahuenig.pdf Siegfried Hünig, in consultation with Albert J. Augustin (Oct. 2007]<!--according to page 47-->). Sehschaden im Alter vorbeugen und mildern. Informationen und Empfehlungen zur altersbedingten Makuladegeneration und zum grauen Star. [Preventing and Alleviating Vision Damage at Higher Age. Information and Recommendations for Age-Related Macular Degeneration]{{cbignore|bot=medic}}. ''Manuscript hosted on the website of [[hospital|Klinikum]] [[Karlsruhe]]'' (retrieved 21 September 2009)<br />[http://www-organik.chemie.uni-wuerzburg.de/fileadmin/08020000/user_upload/makula/optimiert_teil2.pdf{{Dead link|date=January 2020 |bot=InternetArchiveBot |fix-attempted=yes }} Siegfried Hünig (2008). Optimierter Lichtschutz der Augen. Eine dringende Aufgabe und ihre Lösung. Teil 1: Beschaffenheit des Lichts, innere und äußere Abwehrmechanismen. [Optimized protection from light-inflicted eye damage. A pressing problem and a simple solution<nowiki>]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</nowiki>]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}. ''Zeitschrift für praktische Augenheilkunde, 29,'' pp. 111-116.<br />[http://www-organik.chemie.uni-wuerzburg.de/fileadmin/08020000/user_upload/makula/optimiert_teil2.pdf{{Dead link|date=January 2020 |bot=InternetArchiveBot |fix-attempted=yes }} Siegfried Hünig (2008). Optimierter Lichtschutz der Augen. Teil 2: Sehprozess als Risikofaktor, Lichtschutz durch Brillen [Optimized protection from light-inflicted eye damage. A pressing problem and a simple solution<nowiki>]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</nowiki>]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}. ''Zeitschrift für praktische Augenheilkunde, 29,'' pp. 197-205.</ref> Sunglasses are not sufficient to protect the eyes against permanent harm from looking directly at the Sun, even during a [[solar eclipse]]. Special eyewear known as [[solar viewer]]s are required for direct viewing of the sun. This type of eyewear can filter out UV radiation harmful to the eyes.<ref name="live_Will">{{Cite web| title = Will Your Solar Eclipse Glasses Still Be Safe to Use in 2024?| author = Weisberger, Mindy| work = Live Science| date = 2017-08-25| access-date = 2017-08-28| url = https://www.livescience.com/60237-do-solar-eclipse-glasses-expire.html| url-status = live| archive-url = https://web.archive.org/web/20170827050559/https://www.livescience.com/60237-do-solar-eclipse-glasses-expire.html| archive-date = 2017-08-27}}</ref>

More recently, [[high-energy visible light]] (HEV) has been implicated as a cause of age-related macular degeneration;<ref>{{cite journal | pmid = 16395131 | volume=26 | title=Could blue light-blocking lenses decrease the risk of age-related macular degeneration? | date=January 2006 | journal=Retina (Philadelphia, Pa.) | pages=1–4  | last1 = Glazer-Hockstein | first1 = C | last2 = Dunaief | first2 = JL | issue=1 | doi=10.1097/00006982-200601000-00001}}<br />{{cite journal | last1 = Margrain | first1 = TH | last2 = Boulton | first2 = M | last3 = Marshall | first3 = J | last4 = Sliney | first4 = DH | date = Sep 2004 | title = Do blue light filters confer protection against age-related macular degeneration? | journal = Prog Retin Eye Res | volume = 23 | issue = 5| pages = 523–31 | doi = 10.1016/j.preteyeres.2004.05.001 | pmid = 15302349 | s2cid = 40276594 }}</ref> before, debates had already existed as to whether "blue blocking" or amber tinted lenses may have a protective effect.<ref name="AAO">American Academy of Ophthalmollogy. {{usurped|1=[https://web.archive.org/web/20111127121646/http://www.aao.org/aaoesite/eyemd/upload/Sunglasses.pdf "Information from Your Eye M.D.: Sunglasses."]}} November 2003.</ref> Some manufacturers already design glasses to block blue light; the insurance company [[Suva (insurer)|Suva]], which covers most [[Switzerland|Swiss]] employees, asked eye experts around Charlotte Remé ([[ETH Zürich]]) to develop norms for blue blocking, leading to a recommended minimum of 95% of the blue light.<ref>Article by Charlotte Remé, who also developed the guidelines/norms for Switzerland:<br />{{cite journal | last1 = Remé | first1 = Charlotte | year = 1997 | title = Lichtschutz der Augen. [Light protection for Eyes] | journal = Der informierte Arzt – Gazette Médicale | volume = 18 | pages = 243–246 }}</ref> Sunglasses are especially important for children, as their ocular lenses are thought to transmit far more HEV light than adults (lenses "yellow" with age).

There has been some speculation that sunglasses actually promote [[skin cancer]].<ref>{{cite web|url=http://www.express.co.uk/posts/view/8739/Sunglasses+raise+risk+of+cancer|title=Sunglasses Raise Risk of Cancer|publisher=Express.co.uk|date=2007-06-03|access-date=2010-05-13}}</ref> This is due to the eyes being tricked into producing less [[melanocyte]]-stimulating [[hormone]] in the body.

==== Assessing protection ====
[[File:Stanley Vexis Gray Lens RST-61066 safety glasses.jpg|thumb|right|These safety sunglasses have a scratch resistant coating, block 99.9% UV, and meet ANSI Z87.1 and CSA Z94.3 standards.]]

The only way to assess the protection of sunglasses is to have the lenses measured, either by the manufacturer or by a properly equipped [[optician]]. Several standards for sunglasses (see [[#Standards for sunglasses|below]]) allow a general classification of the UV protection (but not the blue light protection), and manufacturers often indicate simply that the sunglasses meet the requirements of a specific standard rather than publish the exact figures.

One "visible" quality test for sunglasses is their fit. The lenses should fit close enough to the face that only very little "[[stray light]]" can reach the eye from their sides, or from above or below, but not so close that the eyelashes smear the lenses. To protect against "stray light" from the sides, the lenses should fit close enough to the temples or merge into broad temple arms or leather blinders. Another test is for lenses said to be polarising: having two such lenses, they should block all light when after each other with one pair turned 90°.

It is not possible to "see" the protection that sunglasses offer. Dark lenses do not automatically filter out more harmful [[Ultraviolet|UV radiation]] and blue light than light lenses. Inadequate dark lenses are even more harmful than inadequate light lenses (or wearing no sunglasses at all) because they provoke the pupil to open wider. As a result, more unfiltered radiation enters the eye. Depending on the manufacturing technology, sufficiently protective lenses can block much or little light, resulting in dark or light lenses. The lens color is not a guarantee either. Lenses of various colors can offer sufficient (or insufficient) UV protection. Regarding blue light, the color gives at least a first indication: Blue blocking lenses are commonly yellow or brown, whereas blue or gray lenses cannot offer the necessary blue light protection. However, not every yellow or brown lens blocks sufficient blue light. In rare cases, lenses can filter out too much blue light (i.e., 100%), which affects color vision and can be dangerous in traffic when colored signals are not properly recognized.

High prices cannot guarantee sufficient protection as no correlation between high prices and increased UV protection has been demonstrated. A 1995 study reported that "Expensive brands and polarizing sunglasses do not guarantee optimal UVA protection."<ref name="Leow">{{cite journal | last1 = Leow | first1 = YH | last2 = Tham | first2 = SN | date = Nov 1995 | title = UV-protective sunglasses for UVA irradiation protection | journal = Int J Dermatol | volume = 34 | issue = 11| pages = 808–10 | pmid = 8543419 | doi=10.1111/j.1365-4362.1995.tb04405.x| s2cid = 45093664 }}</ref> The [[Australian Competition & Consumer Commission]] has also reported that "[c]onsumers cannot rely on price as an indicator of quality".<ref>{{cite web|url=http://www.accc.gov.au/content/index.phtml/itemId/614116/fromItemId/692835 |archive-url=https://web.archive.org/web/20060212021726/http://www.accc.gov.au/content/index.phtml/itemId/614116/fromItemId/692835 |url-status=dead |archive-date=2006-02-12 |title=Sunglasses and fashion spectacles—April 2003 |publisher=Accc.gov.au |access-date=2010-05-13 }}</ref> One survey even found that a $6.95 pair of generic glasses offered slightly better protection than expensive [[Salvatore Ferragamo]] shades.<ref>{{cite web | title=Some Sunglasses Are Cheap In Price Only|url=http://wcbstv.com/seenon/UV.Rays.Sunglasses.2.234545.html|author=Cole, Kirstin|publisher=CBS|archive-url=https://web.archive.org/web/20080514190937/http://wcbstv.com/seenon/UV.Rays.Sunglasses.2.234545.html|archive-date=14 May 2008}}</ref>

=== Further functions ===
[[File:Schlagersänger Heino.jpg|thumb|left|Protecting his eyes from exposure due to [[exophthalmos]], sunglasses have become the trademark of German singer [[Heino]].]]

While non-tinted glasses are very rarely worn without the practical purpose of correcting eyesight or protecting one's eyes, sunglasses have become popular for several further reasons, and are sometimes worn even indoors or at night.

Sunglasses can be worn to hide one's eyes. They can make [[eye contact]] impossible, which can be intimidating to those not wearing sunglasses; the avoided eye contact can also demonstrate the wearer's detachment,{{Citation needed|date=September 2009}} which is considered desirable (or "[[cool (aesthetic)|cool]]") in some circles. Eye contact can be avoided even more effectively by using [[mirrored sunglasses]]. Sunglasses can also be used to hide emotions; this can range from hiding blinking to hiding [[Crying|weeping]] and its resulting red eyes. In all cases, hiding one's eyes has implications for [[nonverbal communication]]; this is useful in [[poker]], and many professional poker players wear heavily tinted glasses indoors while playing, so that it is more difficult for opponents to read [[tell (poker)|tells]] which involve eye movement and thus gain an advantage.

[[File:Tuska 20130630 - Amaranthe - 11.jpg|thumb|right|333px|Artist [[Elize Ryd]] wearing sunglasses as part of her costume for the [[Tuska Open Air Metal Festival]]]]Fashion trends can be another reason for wearing sunglasses, particularly designer sunglasses from high-end fashion brands. Sunglasses of particular shapes may be in vogue as a [[fashion accessory]]. The relevance of sunglasses within the fashion industry has included prominent fashion editors' reviews of annual trends in sunglasses as well as runway fashion shows featuring sunglasses as a primary or secondary component of a look.<ref>{{cite web|url=http://www.harpersbazaar.com/fashion/fashion-week/g2974/best-sunglasses-nyfw-spring14/ |title=Best Sunglasses of 2014 from New York Spring Fashion Week |date=13 September 2013 |access-date=2015-03-19 |url-status=live |archive-url=https://web.archive.org/web/20160820002234/http://www.harpersbazaar.com/fashion/fashion-week/g2974/best-sunglasses-nyfw-spring14/ |archive-date=2016-08-20 }}</ref> Fashion trends can also draw on the "cool" image of sunglasses and association with a particular lifestyle, especially the close connection between sunglasses and beach life. In some cases, this connection serves as the core concept behind an entire brand.

People may also wear sunglasses to hide an abnormal appearance of their eyes. This can be true for people with severe visual impairment, such as the [[blindness|blind]], who may wear sunglasses to avoid making others uncomfortable. The assumption is that it may be more comfortable for another person not to see the hidden eyes rather than see abnormal eyes or eyes which seem to look in the wrong direction. People may also wear sunglasses to hide dilated or contracted pupils, bloodshot eyes due to drug use, chronic dark circles or crow's feet, recent physical abuse (such as a [[black eye]]), [[exophthalmos]] (bulging eyes), a [[cataract]], or eyes which jerk uncontrollably ([[Physiologic nystagmus|nystagmus]]).

Lawbreakers have been known to wear sunglasses during or after committing a crime as an aid to hiding their identities.<ref>{{cite news |url=http://abclocal.go.com/ktrk/gallery?id=8816697&photo=2 |title=10 most wanted bank robbery suspects |quote=In each of the instances, the female suspect wore a distinctive wig and sunglasses to conceal her identity. |date=2012-09-19 |publisher=ABC Local |access-date=2012-11-26 |url-status=dead |archive-url=https://archive.today/20130124060140/http://abclocal.go.com/ktrk/gallery?id=8816697&photo=2 |archive-date=2013-01-24 }}</ref>