An eyelash or simply lash is one of the hairs that grows at the edge of the
eyelid. Eyelashes protect the eye from debris and perform some of the same
function as whiskers do on a cat or a mouse in the sense that they are
sensitive to being touched, thus providing a warning that an object is
near the eye. The Ancient Greek word for eyelash is
βλέφαρον, which is seen as a root in biological terms like Blephara and
Katoblephara. Structure
= Development= The eyelashes of the 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 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. = Glands=
The follicles of eyelashes are associated with a number of glands known
as the glands of Zeis and the glands of Moll.
Clinical significance 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 external hordeolum, or stye, is a purulent inflammation of infected
eyelash follicles and surrounding sebaceous and apocrine glands of the lid
margin. Trichotillomania is a disorder that
urges the sufferer to pull out scalp hair, eyelashes, etc.
Demodex folliculorum is a small mite that lives harmlessly in eyelash and
other hair follicles, and about 98% of people have these mites living on them.
Occasionally they may cause blepharitis. Eyelash and eyebrow transplant surgeries
may be help to reconstruct or thicken lashes or eyebrow hair.
Society and culture = Cosmetics=
Long eyelashes are considered a sign of beauty in many cultures. Accordingly,
some women seek to enhance their eyelash length artificially, using eyelash
extensions. On the other hand, Hadza women are known to trim their own
eyelashes. Kohl, a black putty, has been worn as
far back as the Bronze Age to protect and enhance lashes. In Ancient Egypt, it
was used as well by the wealthy and the royal to protect their eyes from the
sand, dust, and bugs. 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. There are also different
tools that can be used on the lashes such as eyelash curler or mascara
shield. Permanent eyelash tints and eyelash
extensions have also become popular procedures, even in fairly basic salons.
It is also possible to get 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.
Latisse was introduced in the first quarter of 2009 by Allergan as the first
drug to receive FDA approval for eyelash growth. Latisse is a solution of
bimatoprost, 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. 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 your
lashes. Many utilize seed extract, minerals, and other chemicals to achieve
these results. In other animals
Lashes, being hair, are found in mammals. Camels' lashes are remarkably
long and thick. Horses and cows feature eyelashes as well. Inherited eyelash
problems are common in some breeds of dogs as well as horses.
Hornbills have prominent eyelashes, as do ostriches, but they are an uncommon
feature in birds. Eyelash vipers show a set of modified scales over the eyes
which look much like eyelashes. References
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