3.1 Eye anatomy and lash cycles

There are two components of the human body that are of particular interest to the lash technician: the eyelid and the eyelash. You would be forgiven for assuming we might jump straight into an examination of the eyelash, given the fact we are studying a course in lash mastery! However, as you’ll soon learn, it is the skin within which the eyelash is housed that provide for some of the eyelash’s most defining characteristics.

Defining the eyelid

In basic terms, the eyelids are folds of skin and tissue connected to a muscle (called the orbicularis occuli) that open and close either voluntarily (i.e. to sleep) or involuntarily (blinking or reflex). The upper eyelid is defined as starting at the eyelid margin (the very edge of the eyelid where the eyelashes grow) and extending to the base of the eyebrow. The lower eyelid again starts at the eyelid margin, and extends to the crease in the skin at the top of the cheek. The primary role of the eyelid is to keep the surface of the eye (cornea) moist, which is achieved by the spreading of tears (a film discharged from the tear duct) every time we blink. Secondary to this, when closed, the eyelids protect the eye from from foreign objects and light.

Fun fact: The number of eyelashes on each lid range widely as the top eyelid usually accommodates approximately 70 to 150 individual hairs, while the bottom eyelid may have somewhere between 30 and 100 hairs.

Eyelid skin: the thick and thin of it

To understand the peculiarities of the skin of the eyelids, it is helpful to compare it with the skin of the scalp (which is similar to the skin on much of the remainder of the body). The skin on the scalp contains three layers: the epidermis (external), the dermis (middle) and the hypodermis (internal), as you can see in the below diagram.

Anatomy of scalp hair consisting of three layers: the epidermis, the dermis, and the hypodermis

The skin of the eyelids, however, consists of only two layers: the epidermis (which is much thinner than the epidermis of the scalp) and the dermis. As a result, the skin of the eyelid is much thinner than that on the scalp, and the thinnest of any region of the body at lass than 1mm in thickness.

In terms of how this affects the eyelash (your canvas!), all hair follicles on the human body are rooted in their deepest skin layer, notably the hypodermis on the scalp and the dermis within the eyelid. Consequently, the eyelash follicle is shorter than the scalp hair follicle, resulting in a much shorter and finer hair shaft.

In addition to their relatively short length and fine composition, another defining property of an eyelash is its curved shape, a characteristic present in all ethnicities. The science behind exactly what causes this phenomenon is far too in depth for a lash mastery course (even the most comprehensive and educational course on the net!). However, in basic terms, this curvature is a result of asymmetric (or uneven) cell development in the hair root within the dermis of the eyelid, resulting in the concave (or inner) side of the hair being thicker and the convex (or outer) side of the hair being thinner. The eyelash therefore essentially grows ‘around’ the thicker, more tightly-packed cells on the inside of the curve (or curl).

Finally, while not necessarily a characteristic that will impact your profession as a lash technician (but may come in handy during a trivia night!), one final difference between eyelashes and other hair on the body is the absence of an arrector pili muscle. The arrector pili is an extremely small muscle that attaches to the hair shaft within the dermis and is responsible for the straightening of the hair in response to cold or intense emotions (commonly referred to as goose bumps).

Sense and sensitivity

The relative thinness of the skin layer in itself would suggest that the eyelids are a particularly delicate area of the human body. However, the skin of the eyelid also contains a relatively high amount of blood vessels and very little fat compared with other areas of skin. All of these characteristics combined equate to the skin of the eyelids being extremely susceptible to irritation and more prone to allergic reactions. We’ll explore irritations and reactions later in this module.

The eyelash

Now that we have a firm grasp on the eyelid and a few of its more unique characteristics, let’s progress to an in-depth examination of that which will be your canvas for many years to come: the eyelash.

Far from simply serving an aesthetic purpose, eyelashes perform a number of important functions as the first line of defence for the eye. In addition to keeping out small foreign objects like dust and insects, they also act to shield the eye from the elements: wind, rain and sunlight. Perhaps the most interesting function they perform, however, is to initiate what is known as the ‘protective response’. Each eyelash is connected at its root to a hair plexus, which is a special group of nerve fibre endings that serve as an extremely sensitive receptor for touch sensation. In a similar fashion to the function of whiskers on a cat or a mouse, when an object touches an eyelash, a signal is passed to the brain extremely quickly, warning of a foreign object in close proximity to the eye. In response, the brain reflexively signals the eyelids to close.

Eyelash properties

Similar to other hair on the body and scalp, eyelash hair is comprised of approximately 90% proteins (including keratin and melanin) and 10% water, and receives nourishment from blood vessels within the hair root. However, as we touched on in the previous lesson, that is about where the similarities cease.

Eyelashes are much shorter and finer than scalp hair, with a length of approximately 4–14mm depending on factors such as location (on the eyelid margin), race and age. The upper eyelid houses approximately 80-150 individual lashes arranged in two to four rows. Upper eyelashes are more numerous and longer than lower lashes and curve upward. The lower eyelid will generally contain approximately 70-100 downward-curving lashes.

Fun fact: On average, 1 to 5 lashes fall out every day. New lashes grow frequently and replace the lost ones to maintain the complete thick look. So your lashes never get damaged by lash extensions. Lash extensions do not destroy natural lashes; bad technicians do!

The lash itself is made up of three layers that fit into one another, which are the medulla, cortex and cuticle. Let’s learn more about each layer:

The lash itself is made up of three layers that fit into one another. These are:

  • the Medulla: innermost structure that consists of loose cells;
  • the Cortex: this makes up the major part of the fibre (90 percent of total weight) and provides the hair’s strength and stability. The pigmentation of the lash is the result of the melanin contained in the cortex; and
  • the Cuticle: the outermost protective layer which comprises of five to ten layers of non-pigmented flattened cells, arranged like tiles on a roof that overlap.

As also touched on previously, all eyelashes are characterised by a tendency to grow in a curved shape. The degree of curvature is dependent on the asymmetric distribution of cells as they develop in the root of the lash. Studies on eyelash growth across various races have revealed curvature is most apparent in the African race, followed by Caucasian, and least in Asians. Each eyelash extends approximately 2mm into the eyelid and grows at a rate of approximately 0.15mm per day. Within the root of both upper and lower eyelash follicles exist two types of secretory glands that are critical for lash and eye health: the sebaceous glands of Zeis and the apocrine (sweat) glands of Moll. Secretions from these glands protect both the surface of the eyelid and the eye.

Fun fact: The lifespan of a single eyelash ranges out between 60 to 200 days, with the majority of them being shed in about 140 days.

Types of natural lash curls

No two clients are the same, and you will likely encounter a broad range of natural growth patterns when applying lash extensions. Your client may have lashes that are downward facing, straight, slightly curled, over curled or a combination! We will look more at the impact the clients natural lash will have on your selection of the perfect lash extension, but for now, review the growth pattern examples below and see if you can identify your own growth pattern:

The beauty of being a lash technician is that you are actually a magician of sorts because you have control over the final look. Much like a makeup artist can contour away a double chin, a skilled lash technician can correct and manipulate the look of the lashes with strategic placement. For example, if you have a client with a combination natural lash, you can create uniformity through the effective application of lashes. It is important that you understand that clients will have a range of natural lash growth patterns, and you as the lash technician, will need to adjust your application accordingly.

The lash cycle

If you own a dog that is lucky enough to spend time inside your home, you will no doubt be aware of its tendency to shed its coat, especially in spring and autumn, in preparation for the cooler and warmer months. Many people will be surprised to discover that humans shed their hair in an almost identical fashion.

As with the hair on your scalp and body, eyelash hairs grow and shed (or fall out) in an ever-repeating cycle. The only difference when compared with the hair on other parts of the body is the length of the various stages of this cycle. The lash cycle consists of three phases –  Anagen, Catagen and Telogen:

The three (primary) phases of the lash cycle
  • Anagen phase: the growing phase, consisting of approximately four to ten weeks. During this time, the hair will continue to form via cell division in the hair root and result in the hair shaft (the visible component of the hair) extending further and further out of the hair follicle. In the previous two lessons, we discussed the characteristic of eyelash hair to grow much shorter than scalp hair (rarely exceeding 12mm in length). This is due to the relatively short length of the eyelash anagen phase (as mentioned, four to ten weeks) compared with that of scalp hair (3-7 years). Approximately 40 percent of upper and 20 percent of lower eyelashes are in the anagen phase at any one time.
  • Catagen phase: the transition phase, consisting of approximately 12 to 20 days. Following the anagen phase, the hair ceases to grow and the hair follicle shrinks in size and moves toward the surface of the skin. No pigment is produced during this phase of the lash cycle.
  • Telogen phase: the resting and shedding phase, consisting of approximately three to six months. As the name suggests, during this phase the eyelash hairs are simply resting within the hair follicle and not actively growing. During the latter stage of the telogen phase (sometimes referred to as a fourth exogen phase), the new hair has already begun to develop at the base of the hair follicle, and will eventually push (or shed) the old hair out of the follicle. As you can therefore see, there is an overlap of the late telogen and early anagen phase.

Seasonal lash sheds

As touched on, much like your furry canine friend and his or her coat, a greater number of our eyelashes will reach the end of their telogen phase and shed in spring and autumn. There is nothing you can do as a lash technician to prevent this natural occurrence, however, educating and informing your clients of this phenomenon will prevent them from assuming this avalanche of lash loss was your fault and either making contact with a complaint or, worse still, never making contact again!

Fun fact: The speed of growth is also impacted by the age of the individual. You will lose more eyelashes as you get older, and it will also take longer to grow back. All in all, an eyelash takes approximately 12 weeks to re-grow after it has fallen out. A healthy lifestyle will result in faster growth of your eyelashes.

We will discuss client retention and maintenance towards the end of the course, including recommended appointment intervals and rebooking schedules. However, it is worth mentioning now that it is wise to recommend more frequent infills during the spring and autumn to keep your clients’ lashes looking lush and full (and them happy!).

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