If the eyes are the windows to the soul, then eyelashes are the curtains that cover those windows.
However, the world is indeed unjust; curtains come in various lengths and thicknesses. Some people have so few eyelashes that they will “deeply mourn” for a long time when one falls out, while others have naturally thick lashes. Eyelashes have been with us since we were in our mother’s womb, but what purpose do they serve? Do genetic factors determine the thickness of our eyelashes?
The shape of curled eyelashes is the best way to prevent droplets from entering the eyes.
Eyelashes serve to protect the eyes from harmful particles in the air such as dust, tiny objects, and sand. They help prevent these particles from falling into the eyes. Eyelashes also shield the eyes from sweat or rain. The curled shape of eyelashes is the best way to prevent droplets from entering the eyes. Their primary function is to protect the eyes from excessive light exposure from the sun. They help filter direct sunlight from shining into your eyes while also preventing dust from entering.
On average, humans have 90 to 150 eyelashes on the upper eyelid and about 70 to 80 on the lower eyelid. Eyelashes are primarily composed of 97% keratin and 3% moisture.
In their natural state, eyelashes will not grow longer after reaching a certain length and will fall out naturally. If you pluck an eyelash, it will take about 7 to 8 weeks for it to regrow; however, continuous plucking can damage the hair follicles permanently, preventing further growth. Eyelashes also have a growth cycle, with lashes falling out and regrowing approximately every 150 days.
The number of eyelashes varies from person to person due to various reasons, including genetic factors, nutritional conditions, health status, and personal maintenance habits. Teenagers tend to have longer and fuller eyelashes compared to adults. Their regeneration time is also shorter.
Like many mammals and birds, we have evolved eyelashes that extend beyond the eye sockets (cold-blooded animals do not have eyelashes), and their primary physiological function is to protect our precious eyes.
Camels, often referred to as the ships of the desert, rely heavily on their long and thick eyelashes to combat the scorching winds, sand, and sun. The important functions of human eyelashes include reducing water evaporation from the eyes (estimated to reduce evaporation by up to 50%). The mechanism is as follows: eyelashes form a barrier that redirects airflow away from the eyes, minimizing the likelihood of direct airflow blowing into them, effectively preventing dry eyes. Additionally, eyelashes can block direct sunlight from reaching the eyeball.
The long and thick eyelashes of camels.
Studies have found that many congenital syndromes can stimulate hair growth, leading to longer eyelashes. For example, Cornelia de Lange syndrome and Oliver-McFarlane syndrome can cause patients to have extremely long eyelashes.
Mutations in the FGF5 gene can cause congenital long eyelashes. (FGF stands for Fibroblast Growth Factor, a type of protein that prevents hair from growing too much, and FGF5 controls the expression of the gene that produces this protein).
If the FGF5 gene is silent, long hair will grow, including eyelashes. Some people inherit the silent expression of the FGF5 gene from their parents, leading to congenital long eyelashes. However, such cases are very rare.
Additionally, some patients may experience the side effect of longer eyelashes after taking certain medications. For instance, glaucoma patients using Latanoprost and lung cancer patients using Erlotinib may see stimulation of hair follicle cells, extending their growth cycle, which can lead to longer eyelashes.
Eyelashes also serve a role similar to whiskers.
Small hair fibers can sense when touched, alerting us to nearby dangers around the eyes. These dangers include insects, dust, and debris that could enter the eyes. The eyes and eyelids will close to protect the eyes from harm when there is an external impact. They act as the first layer of protective barriers.
To stimulate eyelash growth, many different methods have been tried: using mascara, eyelash transplants, eyelash growth solutions, and even medications.
Ancient Egyptian women began applying black ointment to their eyelashes as early as 4000 BC to enhance their appearance.
Modern mascara originated in 1913, created from a mixture of coal dust and mineral oil.
Prostaglandin is the only effective ingredient for eyelash growth.
It has been discovered that prostaglandin medications used to treat glaucoma have the side effect of promoting the growth of eyelash follicles, making them longer and thicker. This type of medication has been specifically developed to enhance eyelash growth. For example, La Disi (Latisse) was the first company to have an eyelash growth medication approved by the FDA.
Experts point out that prostaglandin is the only effective ingredient for eyelash growth. Unfortunately, many products marketed for eyelash growth under the name prostaglandin do not actually contain additional prostaglandin.
Additionally, many patients in the U.S. have filed lawsuits against eyelash growth medications; those containing added prostaglandin, even if effective, should be used with caution.
