Eyelashes are small curved hairs located on the upper and lower lid margins of the eyes, respectively, in mammals.
What are eyelashes?
Like the hair on the head, whiskers and eyebrows, eyelashes, Latin cilia, belong to the appendages of the skin. The finely curved and elastic hairs at the edge of the eyelid fulfill important protective functions and have been of great beauty-aesthetic importance to humans for centuries.
Anatomy and structure
Eyelash hairs are composed primarily of keratin, a horny substance found in the skin. Keratin is a collective term for water-insoluble, amino acid-containing fibrous proteins. These firm, elastic fibers are formed from keratinized, dead cells called keratinocytes. The rigid, short bristle hairs (terminal hairs) of the eyelashes are surrounded by sebaceous and sweat glands . The melbom glands and the Zeis glands are sebaceous glands and produce the so-called “eye butter“, a secretion that prevents the tear fluid from overflowing. Eyelash hairs have a lifespan of about 100 – 150 days. After that they fall out and regenerate again. The growth cycle of human eyelashes lasts from 4 weeks to 6 months. The majority of eyelash hairs are constantly in their growth phase – only 10 percent of all eyelash hairs are in the final growth process. The upper eyelid margin includes a dense eyelash ring of about 150 – 250 hairs. At the lower edge of the eyelid, the eyelashes grow much more sparsely with 50 – 150 hairs. The upper and lower lash line also differ in length growth: the average length of the lash hairs is 8 – 12 mm at the top, and only 6 – 8 mm at the bottom. Normally, head hair color and eyelash color are identical – individually pronounced by the proportion of the body’s own hair color pigment melanin.
Function and tasks
The eye lashes perform important protective functions of the eye against sweat, dust, dirt particles and small foreign bodies. They also protect the eye from intense UV radiation. In studies of various mammals, U.S. scientists found that they have a very similar geometric shape of eyelashes – depending on the size of the eye. Their conclusion: long eyelashes have distinct aerodynamic disadvantages compared to short eyelashes. Because of their length, they defy air resistance poorly and promote a high pickup of dirt particles. Thus, long eyelash hairs cause the eye to dry out more quickly. Despite the controversial medical health aspects, long, silky and beautifully curved eyelashes have been considered an essential beauty criterion since ancient times. Even in ancient times, regular use was made of cosmetic eyelash care products, herbal growth preparations and eyelash dyes for women and men. On the one hand, long, black, strong and thick eyelashes were considered très chic, a highly erotic symbol of seduction; on the other hand, the total shaving of facial hair was considered attractive. In ancient Egypt, high priests shaved off all body hair, including eyelashes and brows, as an outward sign of their caste. Even today, eyelash shaving is subject to a variety of fashion aspects as well as ethnic and cultural influences.
Diseases and ailments
In addition to total eyelash loss (madarosis) or eyelash breakage, there are a number of eyelash dysfunctions that can develop into serious damage if not treated. For example, pathological changes in eyelid position lead to trichiasis, a malpositioning of the eyelashes with mechanical irritation of the cornea. Eyelid skin diseases include pigment disorders, fatty deposits (xanthelasma), herpes simplex infections and other cosmetically disturbing skin inflammations, which in turn can cause persistent hair loss. Inflammations of the sebaceous glands, such as the sty, or the chronic inflammation of the meibomian glands, the chalazion, should definitely be treated by a specialist. Painful diseases of the eyelid margins (blepharitis) are often accompanied by infectious conjunctivitis. Another medical indication for eyelash loss is parasitic infestation of the eyelids. If the color of the eyelashes and the structure of the hair suddenly change, the cause may be genetic, metabolic or nutritional disorders. In particular, eyelash loss is observed in cases of stress, significant vitamin deficiency, hormonal fluctuations and cancer diseases with intensive chemotherapy or radiotherapy, as well as after burns.However, incorrect make-up techniques, overdosed or incompatible care products and an excessively aggressive or even completely neglected daily make-up removal ritual are also triggers for alarming eyelash loss or eyelash breakage. The permanent and improper use of mechanical beauty tools, such as the eyelash curler, and constant eyelash tinting in the beauty salon are further risk factors. To combat thinning eyelash growth, the cosmetics industry now offers various growth serums that have been tested by ophthalmologists and dermatologists. Those who suffer from acute eyelash loss often have a long odyssey of time-consuming and costly treatments and applications of preparations behind them. When conventional methods no longer help, the only option is often to go to a cosmetic surgeon. New procedures in transplantation practice, such as the modern I-FUE procedure, provide a remedy. With eyelash transplantation using the I-FUE method, eyelash thickening and eyelash extension are equally possible on the upper and lower eyelid. Depending on hair density and hair structure, about 80 – 150 donor hairs are transplanted. In case of total hair loss, up to 300 grafts are inserted into the hair follicles. The use of scalp hair also offers optical advantages due to strong length growth identical to the hair structure. The transplantation procedure has been tested worldwide and is considered a skin-friendly, pain-free alternative to the conventional strip technique (strip technique). Further advantages: The I-FUE technique does not require the use of a scalpel or sutures and leaves no unsightly scarring. Moreover, the procedure does not require a longer stay in the clinic. The hair removal takes about 30 minutes, the precise insertion into the hair follicle about 45 minutes. Satisfied patients confirm a high growth rate of transplanted donor hair and a minimal risk of injury. In 95 percent of treated patients, the transplanted eyelash hairs regrow healthily and normally.
