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An eyelash refers to one of the hairs that grows at the edge of the eyelid.
Human lashes grow in up to six distinct layers on each upper and lower eyelids.
There are sets of over 200 lashes surrounding each eye.
Eyelashes are at the edges of the eyelids, heightening protection of the eye from dust and debris and triggers the blink reflex.
Eyelashes protect the eye from debris, dust and small particles.
Eyelashes are sensitive to touch, providing a warning that a foreign object is near the eye, which then closes reflexively.
An eyelash is one of the hairs that grows at the edges of the top and bottom eyelids, spanning outwards and away from the eyes.
The lashes grow in up to six layers on each of the upper and lower eyelids.
Eyelashes protect the eye from debris, dust, and small particles, and are highly sensitive to touch, thus providing a warning that an object 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.
The eyelid margin has many nerve endings enveloping the roots of the lashes, giving it sensitivity to very light tactile input even at the tips of the lashes, enabling it to trigger the blink reflex when touched.
Eyelashes are an important component of physical attractiveness, with long prominent lashes giving the illusion of large, gazing eyes, and drawing attention to the eyes.
Eyelashes serve to protect the eye by catching dust and debris.
The eyelashes develop from the ectoderm between the 22nd and 26th week of pregnancy.
Natural eyelashes do not grow beyond a certain length.
There are approximately 100 cilia on each upper eyelid, and 50 on the lower eyelids.
Eyelashes serve four main functions:
Protect the eye from dust and debris by catching them before they can enter the eye
Trigger the blink reflex in the case of a foreign body approaching the eye and touching the lashes.
Regulate or reduce evaporation of the tear film on the cornea.
Protect the conjunctivae from excessive light and ultraviolet radiation, by forming a filamentous curtain-like structure through their arrangement in multiple imperfect rows.
The eyelashes of the human embryo develop from the ectoderm between the 22nd and 26th week of pregnancy.
Eyelashes take about seven to eight weeks to grow back if pulled out.
Constant pulling on eyelashes may lead to permanent damage.
Eyelash 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 and not affected by puberty.
Lash follicles do not have an arrector pili muscle associated with them, making the lashes static.
Lashes do not continually grow to long lengths like scalp hair, and the individual variability in their length is almost solely determined by genetics.
While there is variation in the length of lashes between individuals-3 mm to 10 mm for upper lashes.
Eye lashes do not vary in length by sex or ethnicity, with the upper lashes of humans typically 7 to 8 mm in length regardless of sex, and generally do not exceed 10 mm in length.
Lower lashes average between 5 and 6 mm in length.
In trichomegaly, the lashes may grow exceptionally long occasionally 15 mm for the upper lashes.
The longest lashes usually grow from the center of the eyelid.
Eyelash length, thickness, and darkness decrease significantly with age, so 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..
This is 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.
The typical width of the human eye is 24.2 mm.
The average human eyelash length of 7 to 8 mm.
Longer lashes offer more protection against ultraviolet radiation than their shorter counterparts.
The length of eyelashes in humans vary greatly by individual, but not by sex or ethnicity.
Lashes grow thick at the roots, and taper at the ends.
People of Asian ethnicities have significantly thicker lashes, than people of Caucasian ethnicities: 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.
Eyelashes grow outwards with varying degrees of curl.
People of Caucasian ethnicities have lashes that are more curled than those of Asian ethnicities.
The degree of curling varies significantly even within a population or ethnicity,
The number of individual lashes on the upper eyelid is typically 90 to 160, and on the lower eyelid 75 to 80.
The number of follicles and hence lashes cannot be increased after birth.
The follicles of eyelashes are associated with a number of glands known as the glands of Zeis and the glands of Moll.
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 eyelids are red and itching, the skin often becomes flaky, and the eyelashes may fall out.
Distichiasis refers to 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 external hordeolum, or stye, is a purulent inflammation of infected eyelash follicles and surrounding sebaceous (Gland of Zeis) and apocrine (Moll’s gland) glands of the lid margin.
The eyelash roots are located on the anterior surface of the tarsus.
Cilia travel between the orbicularis oculi and the muscle of Riolan and exit the skin at the anterior lid margin.
Eyelashes fall off by themselves without any need for trimming.
Eyelashes take about seven to eight weeks to grow back if pulled out.
Their color may differ from that of the scalp hair, although they tend to be dark on someone with dark hair and lighter on someone with light hair.
Eyelash hair is not affected by puberty.
The eyelid follicles are associated with the glands of Zeis and the glands of Moll.
Diseases or disorders involving the eyelashes include:
Madarosis is the loss of eyelashes.
Blepharitis is the inflammation of the lid margin.
Distichiasis is the abnormal growth of lashes from certain areas of the eyelid.
Trichiasis (ingrown eyelashes).
Infestation with parasitic crab louse.
Hordeolum, or stye.
Trichotillomania
Demodex folliculorum mites live harmlessly in eyelash and other hair follicles in about 98% of people.
Latisse received FDA approval for eyelash growth.
Latisse is a solution of bimatoprost that provides noticeable eyelash growth within 16 weeks.
Latisse eyelash growth occur primarily on the upper eyelashes
Trichotillomania is a disorder that urges the sufferer to pull out scalp hair, and eyelashes.
Demodex folliculorum is a small mite that lives harmlessly in eyelash and other hair follicles, and about 20% of people have these mites living on them.
Occasionally demodex folliculorum may cause blepharitis.
Trichomegaly is the condition of abnormally long and/or lush lashes.
Eyelash transplant surgery may help to reconstruct lost or damaged lashes, increase the number of lash follicles on the eyelid to enhance the prominence and fullness of the lashes.
The transplanted hairs continue to grow at the same rate as hairs from the area the follicle was extracted from, and require maintenance by means of trimming.
Long eyelashes are coveted as a sign of beauty and 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.
Prominent eyelashes are highly coveted, particularly by women.
Longer and thicker lashes can also have a positive psychological effect on women.
Long, prominent lashes are frequently considered a feminine trait, with studies showing that women possessing longer lashes are perceived as healthier and more feminine.
Long lashes are regarded as an attractive facial feature in both males and females.
An average length eyelash is considered the most attractive across Asian, Indian, Black and White faces.
Eyelashes and lids play a role in eye contact and nonverbal communication.
Voluntarily blinking slowly or a few times in succession quickly is a feminine flirtatious behavior /“bat an eyelash”or “flutter/fluttering eyelashes”.
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.
Eyelashes which are curled are also more prominent, being able to better display their length especially when viewed from the front.
Modern eye makeup includes mascara, eyeliner, eye putty, and eye shadow emphasize the eyes.
Permanent eyelash tints and eyelash extensions have also become popular procedures.
It is also possible to get eyelash transplants:the new eyelashes will continue to grow like head hair and will need to be trimmed regularly.
Latisse is a solution of bimatoprost, a prostaglandin analog and the active component of the glaucoma medication Lumigan.
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.[
Eyelash conditioners are designed to increase the health and length of lashes.
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