Definition

This chapter will give a broad introduction to eye cosmetics. Eyeshadows, mascara, eyeliners, and eyebrow cosmetics will be presented along with the physiology of eyelids, eyelashes, and future trends in the category.

History of eye cosmetics

Cosmetics have been used to adorn the eye for centuries. In Ancient Egypt, materials like charcoal and Kohl were mixed with animal fat to create ointment to darken the lashes and eyelids. The verb used to describe application was “sedjemir” or to “make up the eyes”, which dually meant “to speak or express with the eyes [1].” Ancient Greek and Roman cultures used eye pastes and balms for medicinal uses, but these formulations also contained lapis lazuli and silver to embellish the eye [1]. Ayurvedic cosmetics included substances such as mustard oil, almond oil, and lamp soot, which were used to give the appearance of brighter eyes [2]. In Japan, eyelids were whitened with rice powder and colored with safflower petals [3]. Throughout time and cultures, the purpose of eye cosmetics has remained constant: to accentuate and enhance the beauty of the eye area.

Moving forward to more modern times, in the eighteenth and nineteenth centuries, men would condition their hair and mustaches with a touch‐up product for graying hair called Mascaro. This was also used in stage makeup as both an eyelash and brow cosmetic. In the nineteenth century women darkened their lashes with lamp black, which they could collect simply by holding up a plate to catch the soot above a lamp or candle flame. They also used cake mascara (soap, wax and pigment wetted with a moistened brush) to darken their lashes or they could plump their lashes with petroleum jelly. Since then a wide variety of innovations have changed both the way we decorate eyes and the penetration of these products into daily use by consumers [4].

The first half of the twentieth century saw a range of new product forms emerge including liner pencils, melted wax dripped onto lashes, eyelash curlers, eyebrow pencils, lash dye, cream mascara (toothpaste style tube with brush), false lashes, liquid drops, and even turpentine based waterproof mascara. As the century progressed, more and more women were using eye cosmetics, driven in part by the makeup of the popular actresses in the Hollywood movies and the smoky eyeshadow look of the 1920s. By the late 1930s the majority of women applied cosmetics around their eyes [5].

In 1957, Helena Rubenstein launched the first modern day mascara – a tube of mascara cream with the applicator stored inside the tube. No longer was the mascara applicator separate from the mascara formulation. This efficient and more sanitary design took off quickly, and by the 1960s, this became the standard form of mascara. Once this new product form was established, the applicator quickly changed from a simple grooved aluminum rod to the ubiquitous twisted wire brush applicator that is the predominant applicator today.

By the 1970s, waterproof mascaras were more appealing than the past turpentine‐based versions due to the availability of purified petroleum‐based volatile solvents. Fibers were introduced into mascaras for a “lengthening” benefit. Eyeshadows, due partly to the growth of iridescent pigments in the 1960s, were available in a broad range of matte and sparkling colors. By the 1980s and into the 1990s the rapidly improving performance of polymers resulted in more durable eye cosmetics that would glide on with ease and maintain their effect for hours [6].

From the 2000s onward, eye cosmetics have expanded to meet the demands of the increasingly discerning consumer. Long‐wearing formulas, novel textures, and increased color payoff with minimal fall‐out have become the new standard. Coinciding with the rise of social media and beauty influencer culture, a wide array of innovations in eye cosmetics have allowed the consumer to expand the boundaries of makeup artistry and the overall definition of beauty [7, 8].

Eye physiology

The external eye area is an elaborate network that includes the eyeball and the following accessory structures: eyelids, eyelashes, eyebrows, the lacrimal apparatus, and the underlying eye musculature [9]. While the eyebrows work to divert sweat and particulate matter away from the general eye area, the eyelid and eyelashes serve as physical barriers to the protect the surface of the eye. Due to the sensitivity of the anatomy in the eye area, there are a number of ailments to which the accessory structures are prone, the most common of which are listed in Table 27.1.

Eyelid

The eyelid area is comprised of the upper and lower eyelid. The upper eyelid is a very thin layer of skin that is loosely connected to the underlying structures. Its upward and downward movements are mainly governed by the levator palpebrae superioris and orbicularis oculi muscle, respectively [9]. The lower eyelid is also composed of thin skin and protractor and retractor muscles that aid in eyelid movement and gaze. In addition to the medial and lateral tendons, the orbicularis oculi muscle contributes to the overall shape of the lower eyelid. While there is very little subcutaneous tissue present, the lower eyelid contains three fat pads that, when herniated, create under eye bulges [10].

Eyelid skin is among the thinnest of the body. Indeed, the stratum corneum of the periorbital area is 40% thinner than the rest of the skin on the body. While the eyelid skin itself possesses few oil glands, the eye area contains the highest density of sebaceous glands, primarily due to the meibomian glands at the rim of the eyelid, which produce meibum to prevent tear film evaporation, and the glands of Zeis and Moll, which are glands located along the lid margin to provide lubrication and support to the eyelash [11, 12]. As eyelid skin ages, it loses elasticity and leads to sagging of the skin (Table 27.1).

In order to provide thorough visual information to the brain, the eye performs a variety of involuntary fixational eye movements, or micro‐movements [13]. Additionally, blinking is required to keep the surface of the eye moist and to prevent entry of foreign bodies. The duration of a single blink lasts 0.1–0.4 seconds, resulting in approximately 10,000 blinks per day [14]. Taken together, these ensure that the eye area is in continuous motion. As the skin of the eye area ages, it becomes less adaptable to the stresses of constant movement. In vitro biomechanical analyses showed that compared with younger skin cells, older skin cells were less able to reorient after applied mechanical stress. Furthermore, the applied micro‐movements led to decreased collagen production, cell energy, cell number, and increased inflammation [15]. Figure 27.1 is a summary of the effects of micro‐movements on aging eye skin. Coupled with the thinness of eye area skin, the dynamic nature of this apparatus demands that eye cosmetics must be gentle enough to apply to the delicate surfaces of the eye’s accessory structures, but also durable enough to withstand continuous movement.

Eyelash

Eyelashes are terminal hairs growing from follicles around the eye. Like all hair, the eyelash is a mixture of dead cells that have been keratinized, binding material, melanin granules, and small amounts of water. Keratin makes up ∼95% of the total lash composition, providing lash insolubility and chemical resistance. The outer surface is comprised of a series of overlapping transparent scales called cuticle cells that protect the inside, called the cortex. The cortex contributes to the eyelash’s shape, mechanical properties, and color [12]. Eyelashes can have an elliptical or circular cross section with an average diameter of 60–120 μm, tapering to a fine, barely pigmented tip [12, 16, 17].

While hair over the body provides thermal insulation and proximity sensation, eyelashes protect the eye from debris and signal the eyelid to reflexively close when an object is too close to the eye. Aerodynamic studies performed across 22 mammalian species determined that eyelashes divert airflow and reduce particle deposition and evaporation by up to 50%, and that optimal eyelash length is approximately one third the length of the eye [18]. Chemically, eyelashes are the same as scalp hair, and structurally, the eyelash is very close to curly hair [19]. Eyelashes have a substantially shorter, slower growth phase than scalp hair, hence their shorter length [12, 17], and they typically last for about 3 months before falling out [19]. An active follicle, during the anagen (growth) cycle will typically produce a lash at approximately 0.12–0.14 mm/day, about half the growth rate of scalp hair. Roughly three quarters of the eyelash follicles are in the telogen (resting) phase at any given time [17, 20].

The direction that the eyelash protrudes from the eyelid is based on the follicle’s position in the skin. The curvature of the lash is derived from the plane curved, “comma‐shape” of the follicle, which is about 2 mm long. As the lash forms inside the follicle, and the protein strands are bonded together, the lash shape that is formed corresponds to the shape of the follicle they are formed within [12, 16, 19]. Eyelashes are arranged around the eye in a narrow band 1–2 mm wide, growing in imperfect rows of five to six in the upper and three to four in the lower eyelid [21]. Lashes are longer (8–12 mm) and more numerous (90–200) on the upper eyelid, while lower eyelid lashes number 75–80 and are typically 6–8 mm long [16]. For a single person, lash length varies dramatically, and although lash cycle duration is similar, longer lashes grow faster and for longer than shorter lashes [19]. Figure 27.2 is a series of scanning electron micrographs that show the shape, cross section, and surface morphology of an eyelash.

While it is evident that the physical properties of eyelashes vary by ethnicity (shown in Figure 27.3), very few comparative studies exist that delineate these morphological differences. A study performed between female Asian and Caucasian eyelashes determined that Asian eyelashes had lower curl angles and a greater number of cuticular layers [20]. Lash aging studies performed with White, Black, Hispanic, Asian, and East Asian women showed that eyelash length, thickness, and intensity decreased with age across all ethnicities [22]. A subsequent aging study also determined that lower eyelid lashes on the medial and central eyelid increase curl with age [23].

Eyeshadow

Typically, eyeshadow is color applied to the upper eyelids to add depth and dimension to the eye area. More recent techniques extend application to the lower eyelids to fully complete an eye look. Eyeshadows are generally categorized by finish and can range from matte, low sheen, high sheen, and metallic. A typical matte eyeshadow consists of pigments, binding agents, fillers, and preservatives. Pigments are incorporated at relatively low percentages and the amounts largely depend on the desired end color and payoff. Binding agents can be in liquid or powder form and work to bind the formula together, as well as ensure proper skin adhesion. For liquid binding systems, simple esters are used in order to ensure that the formula maintains product integrity during shipment and over time in a pressed pan. The intensity of a matte eyeshadow can be adjusted by balancing pigment load and fillers. In some instances, this can result in a dry and rough texture. In order to solve for this, a porous mica or creamy powder material and/or different processing steps are needed to balance the formula. Preservatives are necessary to prevent microbial insult or contamination. A standard frost or metallic eyeshadow contains the same elements of matte eyeshadow, but also includes small and large particle pearls. As pearl content increases, more binding agents are required to ensure product integrity and cohesion. Different pearl/pigment combinations allow for a multitude of finishes that can range from a slight sheen to a more luxurious metallic look. While powders are still the primary form, cream to powder, liquid, and creams have become more prevalent.