Editing Eyelash

{{Short description|Facial feature}}
{{other uses}}
{{Infobox anatomy
| Name        = Eyelash
| Latin       = cilium
| Greek       = Bλέφαρον (blépharon)
| Image       = Human eyelashes.jpg
| Caption     = Human eyelashes
| Width       = 
| Image2      =Human eye with eyelid pulled open, anterior view.jpg 
| Caption2    =Human lashes grow in up to six distinct layers on each upper and lower eyelids, in some cases resulting in sets of over 200 lashes surrounding each eye 
| Precursor   = 
| System      = Sensory
| Artery      = 
| Vein        = 
| Nerve       = 
| Lymph       = 
|Function=Lines the edges of the eyelids, heightening protection of the eye from dust and debris and triggers the blink reflex}}
An '''eyelash''' (also called '''lash''') ([[Neo-Latin]]: ''cilium'', plural ''cilia'') is one of the hairs that grows at the edges of the top and bottom [[eyelid]]s, spanning outwards and away from the eyes. The lashes grow in up to six layers on each of the upper and lower eyelids.<ref>{{Cite journal |last1=Aumond |first1=Sarah |last2=Bitton |first2=Etty |date=2018 |title=The eyelash follicle features and anomalies: A review |journal=Journal of Optometry |volume=11 |issue=4 |pages=211–222 |doi=10.1016/j.optom.2018.05.003 |issn=1989-1342 |pmc=6147748 |pmid=30017866}}</ref> Eyelashes serve to protect the [[eye]] from debris, dust, and small particles, and are highly sensitive to touch, thus providing a warning that an object (such as an insect or lint) is near the eye, which then reflexively closes or flutters to rid the area of the object. The eyelid margin from which lashes grow is among the most sensitive parts of the human body, with many [[Nerve|nerve endings]] enveloping the roots of the lashes, giving it sensitivity to very light tactile input even at the tips of the lashes,<ref name=":2">{{Citation |last1=Patel |first1=Bhupendra C. |title=Anatomy, Head and Neck: Eyelash |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK537278/ |work=StatPearls |access-date=2023-05-16 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30725963 |last2=Lopez |first2=Michael J. |last3=Joos |first3=Zachary P.}}</ref> enabling it to trigger the [[Corneal reflex|blink reflex]] when touched.<ref name=":3"/> Eyelashes are also an important component of physical attractiveness, with long prominent lashes giving the illusion of large, gazing eyes,<ref name=":7" /> and drawing attention to the eyes.

== Etymology ==
The word ''eyelash'' is a [[compound word|compound]] consisting of the words ''eye'', referring to the eye which the lashes surround and protect; and ''lash'', referring to the braided cord of a [[whip]] or to the act of stroking with a whip. This is in reference to both the individual lashes resembling whips, and the action of blinking the eyes causing the lashes to move in a stroking or whipping motion.

== Function ==
[[File:Human eye, lateral view.jpg|thumb|260x260px|Eyelashes serve to protect the eye by catching dust and debris. Markedly prominent lashes can be seen here with some dust or debris caught on them]]In humans, the eyelashes serve four main functions:

# Protect the eye from dust and debris by catching them before they can enter the eye
# Trigger the [[Corneal reflex|blink reflex]] in the case of a foreign body approaching the eye and touching the lashes
# Regulate or reduce evaporation of the [[Tears|tear]] film on the [[cornea]]<ref name=":4">{{Cite journal |last1=Amador |first1=Guillermo J. |last2=Mao |first2=Wenbin |last3=DeMercurio |first3=Peter |last4=Montero |first4=Carmen |last5=Clewis |first5=Joel |last6=Alexeev |first6=Alexander |last7=Hu |first7=David L. |date=April 2015 |title=Eyelashes divert airflow to protect the eye |journal=Journal of the Royal Society Interface |language=en |volume=12 |issue=105 |pages=20141294 |doi=10.1098/rsif.2014.1294 |issn=1742-5689 |pmc=4387520 |pmid=25716186}}</ref>
# Protect the [[conjunctiva]]e from excessive light and [[ultraviolet]] radiation, by forming a filamentous curtain-like structure through their arrangement in multiple imperfect rows<ref>{{Cite journal |last1=Paus |first1=R. |last2=Burgoa |first2=I. |last3=Platt |first3=C.I. |last4=Griffiths |first4=T. |last5=Poblet |first5=E. |last6=Izeta |first6=A. |date=April 2016 |title=Biology of the eyelash hair follicle: an enigma in plain sight |url=https://academic.oup.com/bjd/article/174/4/741/6617930 |journal=British Journal of Dermatology |language=en |volume=174 |issue=4 |pages=741–752 |doi=10.1111/bjd.14217|pmid=26452071 |url-access=subscription }}</ref><ref name=":8">{{Cite journal |last1=Marro |first1=Michele |last2=Moccozet |first2=Laurent |last3=Vernez |first3=David |date=2022-02-01 |title=Modeling the protective role of human eyelashes against ultraviolet light exposure |url=https://www.sciencedirect.com/science/article/pii/S001048252100929X |journal=Computers in Biology and Medicine |volume=141 |pages=105135 |doi=10.1016/j.compbiomed.2021.105135 |pmid=34959113 |issn=0010-4825}}</ref>

==Structure==
===Development===
The eyelashes of the human embryo develop from the [[ectoderm]]<ref>{{cite book|last=Standring|first=Susan Neil R. Borley|title=Gray's Anatomy: the Anatomical Basis of Clinical Practice|year=2008|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0443066849|page=703|edition=40th}}</ref> between the 22nd and 26th week of pregnancy.<ref>{{cite web|url=https://www.nlm.nih.gov/medlineplus/ency/article/002398.htm |title=Fetal development: MedlinePlus Medical Encyclopedia |publisher=Nlm.nih.gov |access-date=2013-03-16}}</ref> Eyelashes take about seven to eight weeks to grow back if pulled out, but constant pulling may lead to permanent damage. Their color may differ from that of the [[hair]], although they tend to be dark on someone with dark hair and lighter on someone with light hair. Eyelash hair is not androgenic<ref>{{Cite journal|title = The hair follicle: a paradoxical androgen target organ | pmid=11595812 | volume=54 | year=2000 | journal=Horm. Res. | pages=243–50 | last1 = Randall | first1 = VA | last2 = Hibberts | first2 = NA | last3 = Thornton | first3 = MJ | last4 = Hamada | first4 = K | last5 = Merrick | first5 = AE | last6 = Kato | first6 = S | last7 = Jenner | first7 = TJ | last8 = De Oliveira | first8 = I | last9 = Messenger | first9 = AG | issue=5–6 | doi=10.1159/000053266| doi-broken-date=1 November 2024 | s2cid=42826314 }}</ref> and is therefore not affected by puberty. Lash follicles do not have an [[arrector pili muscle]] associated with them, making the lashes static.<ref name=":3">{{Cite journal |last=Fagien |first=Steven |date=2010-04-13 |title=Management of hypotrichosis of the eyelashes: Focus on bimatoprost |journal=Clinical, Cosmetic and Investigational Dermatology |language=English |volume=3 |pages=39–48 |doi=10.2147/CCID.S5488 |pmc=3047948 |pmid=21437058 |doi-access=free }}</ref>

=== Length ===
Human eyelash length is the subject of extensive studies, both for the effect on their functional efficacy, and for their effect on human physical attractiveness. This is also because lashes do not continually grow to long lengths like [[scalp]] hair, and the individual variability in their length is almost solely determined by [[genetics]].<ref>{{Cite journal |last1=Hutchison |first1=D. M. |last2=Duffens |first2=A. |last3=Yale |first3=K. |last4=Park |first4=A. |last5=Cardenas |first5=K. |last6=Mesinkovska |first6=N. A. |date=April 2022 |title=Eyelash trichomegaly: a systematic review of acquired and congenital aetiologies of lengthened lashes |url=https://onlinelibrary.wiley.com/doi/10.1111/jdv.17877 |journal=Journal of the European Academy of Dermatology and Venereology |language=en |volume=36 |issue=4 |pages=536–546 |doi=10.1111/jdv.17877 |pmid=34919300 |issn=0926-9959|url-access=subscription }}</ref>

While there is considerable variation in the length of lashes between individuals (3&nbsp;mm to 10&nbsp;mm for upper lashes), lashes do not vary in length by [[sex]]<ref name=":0">{{Cite web |title=A study of normal eyelashes in Japanese individuals |url=https://www.oatext.com/A-study-of-normal-eyelashes-in-Japanese-individuals.php |access-date=2023-05-16 |website=www.oatext.com |language=en}}</ref> or [[ethnicity]],<ref name=":1">{{Cite journal |last1=Na |first1=J.I. |last2=Kwon |first2=O.S. |last3=Kim |first3=B.J. |last4=Park |first4=W.S. |last5=Oh |first5=J.K. |last6=Kim |first6=K.H. |last7=Cho |first7=K.H. |last8=Eun |first8=H.C. |date=2006-08-30 |title=Ethnic characteristics of eyelashes: a comparative analysis in Asian and Caucasian females |url=https://doi.org/10.1111/j.1365-2133.2006.07495.x |journal=British Journal of Dermatology |volume=155 |issue=6 |pages=1170–1176 |doi=10.1111/j.1365-2133.2006.07495.x |pmid=17107385 |s2cid=26752340 |issn=0007-0963|url-access=subscription }}</ref> with the upper lashes of humans typically 7 to 8&nbsp;mm in length regardless of sex,<ref name=":0" /> and generally do not exceed 10&nbsp;mm in length.<ref name=":5">{{Cite journal |last1=Thibaut |first1=S. |last2=De Becker |first2=E. |last3=Caisey |first3=L. |last4=Baras |first4=D. |last5=Karatas |first5=S. |last6=Jammayrac |first6=O. |last7=Pisella |first7=P.J. |last8=Bernard |first8=B.A. |date=2009-09-01 |title=Human eyelash characterization |url=https://doi.org/10.1111/j.1365-2133.2009.09487.x |journal=British Journal of Dermatology |volume=162 |issue=2 |pages=304–310 |doi=10.1111/j.1365-2133.2009.09487.x |pmid=19804590 |s2cid=40635760 |issn=0007-0963|url-access=subscription }}</ref> Thus, the lashes of humans are considered to be remarkably long when they are 10&nbsp;mm or greater in length.<ref name=":6">{{Cite web |title=Eyelashes, Long |url=https://elementsofmorphology.nih.gov/index.cgi?tid=b1145bac0932da43 |access-date=2023-05-16 |website=elementsofmorphology.nih.gov}}</ref> Lower lashes average between 5 and 6&nbsp;mm in length.<ref name=":0" /> In [[trichomegaly]], the lashes may grow exceptionally long<ref name=":02">{{Cite journal |last1=Paul |first1=Laura J. |last2=Cohen |first2=Philip R. |last3=Kurzrock |first3=Razelle |date=June 2012 |title=Eyelash trichomegaly: review of congenital, acquired, and drug-associated etiologies for elongation of the eyelashes: Eyelash trichomegaly |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-4632.2011.05315.x |journal=International Journal of Dermatology |language=en |volume=51 |issue=6 |pages=631–646 |doi=10.1111/j.1365-4632.2011.05315.x |pmid=22607279 |s2cid=205398795|url-access=subscription }}</ref> (occasionally 15&nbsp;mm for the upper lashes). The longest lashes usually grow from the centre of the eyelid.<ref name=":1" /> Human eyelash length, thickness, and darkness decrease significantly with age,<ref>{{Cite journal |last1=Glaser |first1=Dee A. |last2=Jones |first2=Derek |last3=Carruthers |first3=Jean |last4=Campo |first4=Antoinette |last5=Moench |first5=Susan |last6=Tardie |first6=Greg |last7=Largent |first7=Joan |last8=Caulkins |first8=Carrie |date=November 2014 |title=Epidemiologic Analysis of Change in Eyelash Characteristics With Increasing Age in a Population of Healthy Women |url=https://journals.lww.com/dermatologicsurgery/Abstract/2014/11000/Epidemiologic_Analysis_of_Change_in_Eyelash.8.aspx |journal=Dermatologic Surgery |language=en-US |volume=40 |issue=11 |pages=1208–1213 |doi=10.1097/DSS.0000000000000170 |issn=1076-0512 |pmid=25347452 |s2cid=24703542|url-access=subscription }}</ref> hence long and thick lashes are sometimes seen as a mark of fertility and youthfulness.

Eyelash length is closely linked to the width of the eye, with the lashes typically growing to one-third the width of the eye as an evolutionary adaptation to reduce tear film evaporation and dust deposition. Lashes longer or shorter than one-third the width of the eye have been shown to have reduced efficacy in serving their function.<ref name=":4" /> The typical width of the human eye is 24.2&nbsp;mm,<ref>{{Cite journal |last1=Bekerman |first1=Inessa |last2=Gottlieb |first2=Paul |last3=Vaiman |first3=Michael |date=2014 |title=Variations in Eyeball Diameters of the Healthy Adults |journal=Journal of Ophthalmology |language=en |volume=2014 |page=503645 |doi=10.1155/2014/503645 |issn=2090-004X |pmc=4238270 |pmid=25431659 |doi-access=free }}</ref> resulting in the average human eyelash length of 7 to 8&nbsp;mm. This evolutionary trait is perhaps why lashes in humans rarely grow beyond 10&nbsp;mm in length.<ref name=":5" /> However, longer lashes offer more protection against ultraviolet radiation than their shorter counterparts.<ref name=":8" />

=== Thickness ===
[[File:Eyelid.jpg|thumb|The length of eyelashes in humans vary greatly by individual, but not by sex or ethnicity. Short eyelashes are shown in this female subject]]
Lashes grow thick at the roots, and have tapered ends. People of Asian ethnicities have significantly thicker lashes, with an average lash diameter of 71.7 μm, than people of Caucasian ethnicities, with have an average lash diameter of 61.0 μm.<ref name=":1" /> However, the number of lashes on the eyelids is fewer in Asians, who typically have 150 lash hairs on the upper lids, than in Caucasians, who typically have 170 lash hairs on the upper lid.<ref name=":1" />

=== Curvature ===
Eyelashes grow outwards from both upper and lower eyelids, with varying degrees of curl. People of Caucasian ethnicities have lashes that are more curled than those of Asian ethnicities.<ref name=":1" /> However, the degree of curling varies significantly even within a population or ethnicity, where people of Asian ethnicities can also exhibit naturally highly curled lashes.<ref>{{Cite journal |last1=Kwak |first1=Taek-jong |last2=Lee |first2=Sang-min |last3=Cho |first3=Wan-gu |date=August 2002 |title=The character of eyelashes and the choice of mascara in Korean women: The choice of mascara in Korean women |url=http://doi.wiley.com/10.1034/j.1600-0846.2002.20352.x |journal=Skin Research and Technology |language=en |volume=8 |issue=3 |pages=155–163 |doi=10.1034/j.1600-0846.2002.20352.x|pmid=12236884 |s2cid=25356581 |url-access=subscription }}</ref>

=== Density ===
The number of individual lashes on the upper eyelid is typically 90 to 160, and on the lower eyelid 75 to 80.<ref name=":2" /> The number of follicles and hence lashes cannot be increased after birth because all follicles develop during embryogenesis.<ref name=":3" />

===Glands===
The [[Hair follicle|follicles]] of eyelashes are associated with a number of [[gland]]s known as the [[glands of Zeis]] and the [[glands of Moll]]. At the edge of the eyelid, the Meibomian Gland is located as an oil-producing gland, maintaining the health and function of the eyelashes.<ref>{{Cite web |title=What Is Meibomian Gland Dysfunction? |url=https://my.clevelandclinic.org/health/diseases/meibomian-gland-dysfunction |archive-url=http://web.archive.org/web/20250321103236/https://my.clevelandclinic.org/health/diseases/meibomian-gland-dysfunction |archive-date=2025-03-21 |access-date=2025-05-13 |website=Cleveland Clinic |language=en}}</ref>

==Clinical significance==
[[Image:Stye02.jpg|right|thumb|A [[stye]]]]
There are a number of diseases or disorders involving the eyelashes:
*[[Madarosis]] is the loss of eyelashes.
*[[Blepharitis]] is the irritation of the lid margin, where eyelashes join the eyelid.  The eyelids are red and itching, the skin often becomes flaky, and the eyelashes may fall out.
*[[Distichiasis]] is the abnormal growth of lashes from certain areas of the eyelid.
*[[Trichiasis]] refers to ingrown eyelashes.
*Eyelashes may become infested with parasitic [[crab louse]].
*An [[stye|external hordeolum]], or stye, is a [[purulent]] inflammation of infected eyelash follicles and surrounding [[Sebaceous gland|sebaceous]] ([[Gland of Zeis]]) and [[Apocrine sweat gland|apocrine]] ([[Moll's gland]]) glands of the lid margin.
*[[Trichotillomania]] is a disorder that urges the sufferer to pull out [[scalp]] hair, eyelashes, etc.
*''[[Demodex folliculorum]]'' (or the demodicid) is a small [[mite]] that lives harmlessly in eyelash and other [[hair follicle]]s, and about 20% of people have these mites living on them.<ref>{{Cite journal |last1=汪 |first1=作琳 |last2=姚 |first2=余有 |last3=郭 |first3=光明 |last4=吴 |first4=婷 |date=2015 |title=阜阳市某高职大学生蠕形螨感染情况调查 |url=https://www.chndoi.org/Resolution/Handler?doi=10.16766/j.cnki.issn.1674-4152.2015.04.009 |journal=中华全科医学 |volume=13 |issue=4 |doi=10.16766/j.cnki.issn.1674-4152.2015.04.009 |access-date=26 May 2024}}</ref> Occasionally they may cause blepharitis.
*People with [[vernal keratoconjunctivitis]] have longer eyelashes,<ref>{{Cite journal |title=Long Eyelashes in a Case Series of 93 Children With Vernal Keratoconjunctivitis |url=https://publications.aap.org/pediatrics/article/115/1/e86/66931/Long-Eyelashes-in-a-Case-Series-of-93-Children?autologincheck=redirected |access-date=2023-05-16 |journal=Pediatrics | year=2005 |doi=10.1542/peds.2004-1555 | last1=Pucci | first1=Neri | last2=Novembre | first2=Elio | last3=Lombardi | first3=Enrico | last4=Massai | first4=Cristina | last5=Bernardini | first5=Roberto | last6=Caputo | first6=Roberto | last7=Campa | first7=Luciana | last8=Libero | first8=Cinzia de | last9=Vierucci | first9=Alberto | volume=115 | issue=1 | pages=e86–e91 | pmid=15629970 | s2cid=10050289 | url-access=subscription }}</ref> with the increased growth likely a result of the occular inflammation accompanying the condition.
*[[Trichomegaly]] is the condition of abnormally long and/or lush lashes (the objective criteria being lashes of 12&nbsp;mm or greater in length on the upper eyelids).<ref>{{Cite journal |last1=Paul |first1=Laura J. |last2=Cohen |first2=Philip R. |last3=Kurzrock |first3=Razelle |date=June 2012 |title=Eyelash trichomegaly: review of congenital, acquired, and drug-associated etiologies for elongation of the eyelashes: Eyelash trichomegaly |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-4632.2011.05315.x |journal=International Journal of Dermatology |language=en |volume=51 |issue=6 |pages=631–646 |doi=10.1111/j.1365-4632.2011.05315.x|pmid=22607279 |s2cid=205398795 |url-access=subscription }}</ref>

[[Eyelash implants|Eyelash transplant]] surgeries may help to reconstruct lost or damaged lashes. The procedure may also be employed to increase the number of lash follicles on the eyelid to enhance the prominence and fullness of the lashes. The transplanted hairs usually do not have the tapered structure of real lashes, and continue to grow at the same rate as hairs from the area the follicle was extracted from. As such, they require maintenance by means of trimming.

==Society and culture==
[[File:Closed human eye, superior view.jpg|thumb|250x250px|Long eyelashes are coveted as a sign of beauty and are considered an attractive facial feature in many cultures. This adult male has [[trichomegaly]] with notably prominent upper lashes measuring 14 mm long, well over the 10 mm normally considered to be long.<ref name=":6" />]]Prominent, luscious eyelashes have long been considered a sign of [[Physical attractiveness|beauty]] in many cultures, almost universally,<ref>{{Cite journal |last1=Aguinaldo |first1=Erick |last2=Mousavi |first2=Maedeh |last3=Peissig |first3=Jessie |date=2018-09-01 |title=Eyelashes and Attraction: Eyelash Length and Fullness are Significantly Correlated with Facial Attractiveness |journal=Journal of Vision |language=en |volume=18 |issue=10 |pages=1338 |doi=10.1167/18.10.1338 |s2cid=149895886 |issn=1534-7362|doi-access=free }}</ref> and as such are highly coveted, particularly by women.<ref>{{Cite journal |last1=Fagien |first1=Steven |last2=Walt |first2=John G. |last3=Carruthers |first3=Jean |last4=Cox |first4=Sue Ellen |last5=Wirta |first5=David |last6=Weng |first6=Emily |last7=Beddingfield |first7=Frederick C. |date=2013-08-01 |title=Patient-Reported Outcomes of Bimatoprost for Eyelash Growth |url=https://academic.oup.com/asj/article/33/6/789/198333 |journal=Aesthetic Surgery Journal |language=en |volume=33 |issue=6 |pages=789–798 |doi=10.1177/1090820X13495887 |issn=1527-330X|url-access=subscription }}</ref> Having longer and thicker lashes can also have a positive [[Psychology|psychological]] effect on women.<ref>{{Cite journal |last1=Shaikh |first1=M. Y. |last2=Bodla |first2=Ali A. |date=February 2006 |title=Hypertrichosis of the eyelashes from prostaglandin analog use: a blessing or a bother to the patient? |url=https://pubmed.ncbi.nlm.nih.gov/16503779/ |journal=Journal of Ocular Pharmacology and Therapeutics|volume=22 |issue=1 |pages=76–77 |doi=10.1089/jop.2006.22.76 |issn=1080-7683 |pmid=16503779}}</ref> Despite not varying by sex and not being a [[secondary sex characteristic]], long, prominent lashes are frequently considered a [[Femininity|feminine trait]], with studies showing that women possessing longer lashes are perceived as healthier and more feminine.<ref>{{Cite journal |last=Adam |first=Aimee |date=October 2021 |title=Beauty is in the eye of the beautiful: Enhanced eyelashes increase perceived health and attractiveness. |url=http://doi.apa.org/getdoi.cfm?doi=10.1037/ebs0000192 |journal=Evolutionary Behavioral Sciences |language=en |volume=15 |issue=4 |pages=356–367 |doi=10.1037/ebs0000192 |s2cid=214292834 |issn=2330-2933|url-access=subscription }}</ref> Nevertheless, long lashes are regarded as an attractive [[Face|facial feature]] in both males and females.<ref name=":7">{{Cite journal |last1=Pazhoohi |first1=Farid |last2=Kingstone |first2=Alan |date=April 2022 |title=The effect of eyelash length on attractiveness: A previously uninvestigated indicator of beauty. |url=http://doi.apa.org/getdoi.cfm?doi=10.1037/ebs0000243 |journal=Evolutionary Behavioral Sciences |language=en |volume=16 |issue=2 |pages=176–180 |doi=10.1037/ebs0000243 |s2cid=228846079 |issn=2330-2933|url-access=subscription }}</ref> On the other hand, [[Hadza people|Hadza]] women are known to trim their own eyelashes.<ref>{{cite encyclopedia |year=2003 |title=Hadza |encyclopedia=Encyclopedia of Sex and Gender: Men and Women in the World's Cultures, Vol.&nbsp;1 |publisher=[[Springer Science+Business Media|Springer]] |location=New York |isbn=978-0-306-47770-6}}</ref> Nonetheless, an average length eyelash is considered the most attractive across Asian, Indian, Black and White faces.<ref>{{Cite journal |last1=Pazhoohi |first1=Farid |last2=Kingstone |first2=Alan |date=September 2023 |title=Eyelash length attractiveness across ethnicities |journal=Scientific Reports |language=en |volume=13 |issue=1 |pages=14849 |doi=10.1038/s41598-023-41739-5|pmid=37684317 |pmc=10491613 |bibcode=2023NatSR..1314849P }}</ref>

[[Ancient Rome|Ancient Romans]] considered long eyelashes a component of aesthetically ideal eyes. [[Pliny the Elder]] wrote that eyelashes fell out from sexual excess, so women desired long lashes as a symbol of chastity.<ref>[[Pliny the Elder]], [http://www.loebclassics.com/view/pliny_elder-natural_history/1938/pb_LCL353.529.xml ''Natural History''], 11.154.</ref> This may have had medical basis as a symptom of [[syphilis]] is often [[Hair loss|alopecia]] of the lashes,<ref>{{Cite journal |last=Chapel |first=Thomas A. |date=1980 |title=The Signs and Symptoms of Secondary Syphilis |journal=Sexually Transmitted Diseases |volume=7 |issue=4 |pages=161–164 |doi=10.1097/00007435-198010000-00002 |jstor=44965786 |pmid=7455863 |s2cid=34851892 |issn=0148-5717|doi-access=free }}</ref> suggesting that individuals with short or sparse lashes were sexually promiscuous.

The traditional [[Meitei writing system]] has two letters (symbols), related to eyelashes. The letter "ꯄ" ("Paa") symbolises the human eyelash, and its letter name "Paa" itself means "eyelash" in [[Meitei language]]. It has an additional form of letter, known as "Pa Lonsum" ("ꯞ").<ref>{{Cite book |last1=Ghai |first1=Deepika |url=https://books.google.com/books?id=lvScEAAAQBAJ&dq=meitei+script+eye+eyelash&pg=PA130 |title=Machine Learning Algorithms for Signal and Image Processing |last2=Tripathi |first2=Suman Lata |last3=Saxena |first3=Sobhit |last4=Chanda |first4=Manash |last5=Alazab |first5=Mamoun |date=2022-11-18 |publisher=John Wiley & Sons |isbn=978-1-119-86184-3 |pages=130 |language=en}}</ref><ref>{{Citation |title=Meetei Mayek or Meetei script chart |date=2009 |url=https://www.cambridge.org/core/books/court-chronicle-of-the-kings-of-manipur/meetei-mayek-or-meetei-script-chart/788010CFE8284F1940148DAFFAC6F262 |work=The Court Chronicle of the Kings of Manipur |pages=145–148 |editor-last=Arambarn Parratt |editor-first=Saroj Nalini |access-date=2023-10-16 |publisher=Foundation Books |doi=10.1017/UPO9788175968547.006 |isbn=978-81-7596-854-7|url-access=subscription }}</ref><ref>{{Cite web |title=Meetei Mayek: The Script |url=http://tabish.freeshell.org/eeyek/script/ |access-date=2023-10-16 |website=tabish.freeshell.org}}</ref>
{|
|- valign="top"
|[[File:Ancient Meitei character "PAA" (ꯄ) represents as well as means "eyelash".jpg|thumb|Ancient Meitei character "PAA" (ꯄ) represents as well as means "eyelash"]]
|[[File:Meetei Mayek letter PA LONSUM (P).svg|thumb|90px|{{small|Smaller "PAA", known as "PAA LONSUM"}}]]
|}

=== Nonverbal communication ===
The lashes and lids play a role in [[Oculesics|eye contact]] and [[nonverbal communication]]. Voluntarily blinking slowly or a few times in succession quickly is a feminine [[Flirting|flirtatious]] behaviour commonly referred to as to "bat an eyelash", "bat/batting eyelashes", or "flutter/fluttering eyelashes".

===Cosmetics===
[[Image:Green mascara.jpg|thumb|250px|Green mascara]]
Because long eyelashes are aesthetically pleasing and seen as a desirable trait that adds to physical attractiveness, some people seek to enhance their eyelash length artificially, by means of [[eyelash extensions]], false lashes attached to the eyelid, cosmetics, or growth products. Additionally, eyelashes which are curled are also more prominent, being able to better display their length especially when viewed from the front. The enhanced appearance of curled eyelashes can be cosmetically achieved by use of [[eyelash curler]]s, or [[eyelash perm]]s. However, these methods do not physically lengthen the lashes.
 
[[Kohl (cosmetics)|Kohl]], a black putty (usually [[antimony]] sulfide or [[Lead(II) sulfide|lead sulfide]]), has been worn as far back as the [[Bronze Age]] to darken the edge of the eyelid (just at the bottom of the eyelashes). In [[Ancient Egypt]], it was used as well by the wealthy and the royal to beautify their eyes. Modern eye makeup includes [[mascara]], [[eyeliner]], [[eye putty]], and [[eye shadow]] to emphasize the eyes. The twentieth century saw the beginning of convincing false eyelashes, popular in the 1960s.

Permanent eyelash tints and eyelash extensions have also become popular procedures, even in fairly basic salons. It is also possible to get [[Eyelash implants|eyelash transplants]], which are similar in nature to [[hair transplantation]] often done on the head. Since the hair is transplanted from the hair on the head, the new eyelashes will continue to grow like head hair and will need to be trimmed regularly.<ref>{{cite web|url=http://news.xinhuanet.com/english/2006-10/25/content_5248767.htm |archive-url=https://web.archive.org/web/20140218214607/http://news.xinhuanet.com/english/2006-10/25/content_5248767.htm |url-status=dead |archive-date=18 February 2014 |title= Plug and sew eyelashes for women |publisher= Xinhua News |date=25 October 2006 |access-date=2013-03-16}}</ref>

[[Bimatoprost|Latisse]] was introduced in the first quarter of 2009 by [[Allergan]] as the first drug to receive [[Food and Drug Administration|FDA]] approval for eyelash growth. Latisse is a solution of bimatoprost, a [[prostaglandin]] analog and the active component of the [[glaucoma]] medication Lumigan. According to Allergan, noticeable eyelash growth occurs within 16 weeks. Growth is reported to occur primarily on the upper eyelashes, with as much as a 25% increase in length.<ref>{{Cite journal |last=Law |first=Simon K. |date=2010-04-21 |title=Bimatoprost in the treatment of eyelash hypotrichosis |journal=Clinical Ophthalmology |language=English |volume=4 |pages=349–358 |doi=10.2147/OPTH.S6480 |pmc=2861943 |pmid=20463804 |doi-access=free }}</ref> In addition, the past decade has seen the rapid increase in the development of eyelash conditioners. These conditioners are designed to increase the health and length of lashes. Many utilize seed extract, minerals, and other chemicals to achieve these results.<ref>{{Cite journal|title=Jarilla–Coffea extract: a natural cosmetic product that improves eyelash and eyebrow growth in women|year=2019|pmc=6330964|last1=Alonso|first1=M. R.|last2=Damonte|first2=S. P.|last3=Anesini|first3=C.|journal=Clinical, Cosmetic and Investigational Dermatology|volume=12|pages=47–55|doi=10.2147/CCID.S182497|pmid=30666142 |doi-access=free }}</ref>

Cosmetic companies have recently relied on scientific research of prostaglandins and the [[Wnt signaling pathway|Wnt/b-catenin]] signaling pathways to develop eyelash products. Although bimatoprost is effective in promoting increased growth of healthy eyelashes and adnexal hairs, its effectiveness in patients with eyelash alopecia areata is debatable.<ref>{{cite journal|title= Bimatoprost in the treatment of eyelash hypotrichosis |date=26 April 2010 |pmc=2861943 | pmid=20463804 |volume=4 |journal=Clin Ophthalmol |pages=349–58 | last1 = Law | first1 = SK | doi=10.2147/opth.s6480 |doi-access=free }}</ref> Some cosmetic brands have begun using [[peptides]] in their formulation rather than prostaglandins because of regulatory rules in places like Canada and California.<ref>{{cite web|url=https://www.lashluxury.ca/a/blog/the-definitive-guide-to-eyelash-growth-serums |title= What is an eyelash serum? |publisher= LashLuxury |date=30 April 2021 |access-date=2021-06-10}}</ref>

==In other animals==
[[Image:Horse eye 5196.jpg|right|thumb|A horse's eye, showing lashes]]
Lashes, being hair, are found in [[mammal]]s. [[Camel]]s' lashes are remarkably long and thick. [[Horse]]s and [[cow]]s feature eyelashes as well. Inherited eyelash problems are common in some breeds of dogs as well as horses.

Eyelashes are an uncommon but not unknown feature in birds. [[Hornbills]] have prominent eyelashes ([[Vestigiality|vestigial]] feathers with no [[barb (feather)|barbs]]), as do [[ostrich]]es. Amongst the reptiles, only [[Bothriechis schlegelii|Eyelash vipers]] show a set of modified [[scale (zoology)|scales]] over the eyes which look much like eyelashes.

== See also ==
*[[Eyelash extensions]], used to enhance the appearance of length, curliness, fullness, and thickness of natural eyelashes
*[[Eyebrow]]s, an area of short hairs above the eyes on the brow ridges

==References==
{{Reflist}}

{{Commons category|Eyelashes}}

==External links==
*{{Commons-inline|Category:Eyelashes|Eyelashes}}

{{Accessory organs of the eye}}
{{Human hair}}
{{Authority control}}
{{Use dmy dates|date=April 2017}}

[[Category:Eyelash| ]]
[[Category:Facial features]]