When the skin of East Asian single eyelids opens, it follows a micro-crease that’s located too close to the upper eyelashes, resulting in a lack of internal pressure for the inner eyelid layers to move as a single unit. So, when the eyelid opens, the underlying muscle and tarsal plate move independently from the external skin. This makes the eyelid skin near the upper eyelashes to initially roll inwards, instead of clumping together so that the upper skin can drape over on top as in a double eyelid.
When the skin of East Asian double eyelids opens, as the eyelid muscles retract (orbicularis muscle, levator aponeurosis), a properly located crease ― supported by a dominant skin tension line ― applies internal pressure to the layers of the upper eyelid (upper eyelid skin, subcutaneous fat, underlying muscle tissue, tarsal plate). This pressure causes the eyelid layers to ‘sandwich’ together, moving upwards as a single unit, and enabling eyelid skin located above it to drape over, forming the double eyelid.
SKIN CREASE GEOMETRY
The Relationship between Eyeballs & Face Shape
Adult human eyeballs do not vary in statistically significant dimensions regardless of gender, age, and ethnic background.
In contrary, the size of adult human skulls ― which contributes largely to one's face-shape ― do vary in statistically significant dimensions correlated with gender, age, and ethnic background.
Depending on one’s particular face-shape, how the skin wraps around the facial subunits of the periorbital area (spherical eyeball shape), determines the location of skin tension lines that may either support a double eyelid crease to be made or an ideal crease to be reinforced.
RELAXED SKIN TENSION LINES (RSTL)
The Kraissl's lines that run perpendicular to muscle action
Relaxed skin tension lines are produced in living subjects by positioning the body so that the skin is relaxed, and then gently pinching the skin to reveal a crease.
When the topographical skin surface area expands and has a faster growth rate than the underlying biological layers, the skin will crease.
As the crease is aligned with the dominant skin tension line that corresponds to the activation of the levator aponeurosis eyelid muscle, it will form more readily every time the eyelid opens.
EYELID CREASE STIMULATION
How mechanical stress loads are exerted to the skin
The f-tape keeps the eyelid stretched (1) while covering the extended-state eyelid skin from the eyelid margin all the way to, and thus targeting, the dominant skin tension line (2). Various sizes are available for a custom-tailored fit.
The n-tape's upper body grips the upper skin (3) in preparation to be lowered. It compresses the ideal eyelid crease (4) and its non-adhesive midsection prevents eyelashes from sticking onto it (5).
When the n-tape legs are lowered and adhered onto the lower eyelid (6), the pulling force transfers to the n-tape's upper body. This is felt by an increased stretching sensation necessary to trigger mechanotransduction pathways in the skin for gradual but long-term changes.
They're more than just skin deep
Eyelids are the thinnest skin on the human body (0.5 mm). They are one of the first areas to show signs of aging, which include creases.
Although thin, the eyelids are comprised of different layers including fat, muscle, and skin. These vary in their behaviour by the influence of hormonal changes in the body throughout the day.
These changes below the skin can make the entire eyelid swollen, giving the developing ideal crease a challenge to form. Understanding how to reduce swelling in the eyelids will accelerate your crease's progress to full strength.
EYELID WATER RETENTION
Factors that cause eyelids to swell
Accelerating your crease's progress to full strength means you're actively
avoiding the following daily life situations that causes the eyelids to swell:
(Click the triangle to expand)
Sleeping too little.
Usually, inadequate sleep means you have been staying awake for too long. If while staying awake, you have been using a lot of concentration to look at something ― such as watching TV, reading a book, or driving ― then you would have been blinking a lot less. Reduction in the rate of blinking increases the tendency for the eyes to dry out. The dehydration attracts water from other areas near the eye, which causes your eyelid to swell up by water retention.
Adequate sleep (6-8 hours) allows your body to regulate stress hormones and replenish damaged collagen broken down during the day. Cortisol levels in the body would be reduced, dropping blood pressure by 10% to 20%. During sleep, the heart beats more slowly, breathing becomes slower, and muscles relax, causing the body temperature to lower. Inadequate sleep causes the opposite effects, which include increased cortisol levels in the body, by virtue of inefficient regulation of the stress hormone. The cortisol will then inhibit collagen formation in the eyelid skin, which causes the skin to adhere itself to the underlying tissues, developing a grove or crease when the eyelid muscles are retracted.
The increased cortisol levels will also raise your heart rate, speed up your breathing, tense your muscles, and ultimately increase your body temperature. As your body temperature increases during inadequate sleep, your body will attempt to achieve homeostasis of a cooler body temperature by secreting aldosterone from the adrenal glands. Aldosterone causes the kidneys to hold onto more sodium. The cortisol also inhibits sodium loss through the small intestine. This further aids in the increase of sodium. Higher sodium levels in the body increase water retention, which causes the fatty areas near your eyes ― subcutaneous fat, orbital fat, fatty eyebrow pad ― to swell.
Sleeping too much.
Sleeping flat on your back for prolonged periods of time makes it easier for water to be retained in the facial tissues. If the head were elevated by use of extra pillows or an adjustable bed, excess water would be assisted to flow out from that region, accumulating in other body parts of lower elevation in relation to your head. One should identify the right elevation level since excessive elevation of head can lead to neck pain and backaches.
Crying before sleeping.
Tears originate from the tear glands, known as the lacrimal glands, located on the upper and outer corners of the eyelids. When you cry, the generation of tears applies considerable pressure onto the lacrimal glands, causing the eyelids to swell. When wiping or rubbing the eyes during crying, the tears consisting of sodium, lands below and around the eyes, dehydrating the neighbouring skin. The dehydration attracts water from other areas near the eye, which causes your eyelid to further swell up by water retention.
Eating too many salty foods, especially shortly before sleeping.
Excessively consuming sodium rich foods, such as salty snacks and processed foods, increases the sodium concentration in the blood stream, causing dehydration and triggering the body's homeostatic mechanism, leading to water retention in the tissues and eyelids.
Drinking alcohol before sleeping.
Drinking alcohol creates a cascade series of chemical reactions that ultimately affects the brain to inhibit the production of ADH, a hormone produced in the hypothalamus and secreted by the posterior pituitary gland. ADH (anti-diuretic hormone) causes the kidneys to reabsorb water, excreting less of it in the urine, thus conserving water. A reduction in ADH means more water would be excreted in the urine, raising sodium concentrations in the blood, dehydrating the body. By homeostasis, the other parts of the body would begin to conserve water by water retention, causing the skin and eyelids to swell.
Another reason why East Asians can be susceptible to a puffy face, even while consuming alcohol in moderation, is because of alcohol flush reaction. Alcohol flush reaction is an allergic reaction to alcohol characterized by nausea, rapid heartbeat and a red, swollen face.
The allergy is caused by an inherited enzyme deficiency common among East Asians. The enzyme, ALDH2, metabolizes alcohol into acetate. Without ALDH2, alcohol would enter the bloodstream as acetaldehyde, a toxin known to cause swelling and puffiness.