New Insights Into the Anatomy of the Eyelashes With Regard to Ethnic Differences Against a Clinical Background.

BACKGROUND: To investigate the root depth, root angle, and light and scanning electron microscopical anatomy of human eyelashes relevant to eyelash ablation. METHODS: Eyelash root depth, the angle between eyelash root and skin epithelium, spatial relationship, and scanning electron microscopical features of the eyelashes were studied on 4 upper and 4 lower eyelids of Caucasian (n = 4) and Indian (n = 4) cadaver heads according to a set protocol. RESULTS: There were significant differences in the mean eyelash root depth between Indians (2.3 ± 0.38 mm) and Caucasians (1.9 ± 0.26 mm; p = 0.007), as well as between upper eyelids and lower eyelids (1.9 ± 0.2 mm vs. 1.8 ± 0.1 mm). The mean angle between the lash follicle root and the skin epithelium was 75 ± 11 degrees and similar in both ethnic groups. The eyelash bulb was located close to the tarsal plate and meibomian glands and formed an angle of less than 15 degrees with the eyelash root. Scanning electron microscopy studies revealed that the eyelash bulb was 202 ± 12 µm wide in Indians and 170.6 ± 16.8 µm wide in Caucasian eyelids ( p = 0.08). The eyelashes were placed more closely in Indian eyelids than in Caucasian eyelids ( p = 0.03). The width of the cuticle layer varied between the hair shaft and the inner eyelid segment. CONCLUSIONS: There are differences in eyelash root depth, inter-eyelash distance, and cuticle thickness between Indian and Caucasian eyelids. The oblique orientation of the eyelash root and close proximity of the eyelash bulb to the tarsal plate should be kept in mind while doing the electroepilation procedure.

How eyelashes can protect the eye through inhibiting ocular water evaporation: a chemical engineering perspective.

Bionics is a fascinating subject that has inspired many inventions through learning from biological structures and functions. In this work, a coupled multi-physics model has been developed to characterize ocular water evaporation with realistic eyelash structures taken into account. From a chemical engineering perspective, the protective function of human eyelashes in terms of evaporation inhibition has been rationally revealed. Systematic investigations were carried out to elucidate the effects of different eyelash lengths, orientations and inlet air directions on water evaporation on the ocular surface. The results clearly demonstrate that regardless of inlet air directions and eyelash orientations, increasing eyelash length from zero to an optimal length can effectively reduce water evaporation. However, further increase in the eyelash length can lead to enhanced evaporation. For the normal and parallel inlet air directions, the optimal eyelash length is around 15-30% of the eye width and can offer approximately 10-30% evaporation reduction when compared with the cases without eyelashes. These values are independent of the eyelash orientation. This investigation provides valuable data for in-depth understanding of the protective function of the eyelashes, which can be used in the future to improve and optimize bionic designs inspired by human eyelashes.

The eyelash follicle features and anomalies: A review / Características y anomalías del folículo de la pestaña: revisión

The primary role of eyelashes is to protect and maintain the health of the lid margin. However, the mechanisms to fulfill this role are not fully understood. Unraveling these mechanisms will stand to greatly improve the efficiency of eye care professionals’ interventions in anomalies of the eyelashes. The aim of this article is to provide a review on eyelashes including highlights and new avenues for research; the biology of both the lash and its follicle; the pathophysiology and management of lash anomalies by eye care professionals; and the effect of iatrogenic factors on lashes. Using the database of Ovid MEDLINE, we reviewed studies specifically directed on human/mammalian eyelashes and key articles on current trends in scalp hair methodologies that can be applicable to lash research. The eyelash morphology, pigmentation and growth rate have been documented using techniques ranging from lash imaging to follicle immunohistochemistry. Furthermore, studies have demonstrated that the lash follicle is sensitive to many factors of the external environment, a variety of systemic/topical medications and cosmetics. Recently, aerodynamic studies using a mammalian eye model confirmed that an optimal lash length was needed so that eyelashes serve a protective role in reducing the number of particles that can reach the eye. Despite recent advances in lash research, studies are still scarce, due to the limited availability of the human lid for sampling. This review brings awareness that further research is needed with respect to eyelashes and will hopefully reduce the gap with scalp hair research

La función principal de las pestañas es proteger y mantener la salud del margen palpebral. Sin embargo, los mecanismos de desempeño de esta función no se comprenden plenamente. Desentrañar estos mecanismos ayudará a mejorar la eficiencia de las intervenciones de los profesionales de cuidados oculares en cuanto a las anomalías de las pestañas. El objetivo de este artículo es aportar una revisión sobre las pestañas, incluyendo los aspectos más destacados y las nuevas aportaciones para la investigación, la biología de la pestaña y su folículo, la patofisiología y tratamiento de las anomalías de las pestañas por parte de los profesionales de cuidados oculares, y el efecto de los factores iatrogénicos sobre las pestañas. Utilizando la base de datos de Ovid MEDLINE, revisamos los estudios específicamente dirigidos a las pestañas humanas/de mamíferos, así como los artículos clave sobre las tendencias actuales en cuanto a las metodologías del cuero cabelludo, que pueden aplicarse a la investigación sobre las pestañas. Se han documentado la morfología de las pestañas, así como su pigmentación y tasa de crecimiento, utilizando técnicas que oscilan entre la imagen de las pestañas y la inmunohistoquímica del folículo. Además, los estudios han demostrado que el folículo de la pestaña es sensible a diversos factores del entorno externo, diversas medicaciones sistémicas/tópicas y cosméticos. Recientemente, los estudios aerodinámicos que han utilizando un modelo de ojo de mamífero, han confirmado que se precisaba una longitud de pestañas óptima para que éstas ejercieran su función protectora a la hora de reducir el número de partículas que pueden acceder al ojo. A pesar de los avances recientes de la investigación sobre las pestañas, los estudios son aún escasos, debido a la disponibilidad limitada de párpado humano para muestreo. Esta revisión sirve de concienciación acerca de la necesidad de investigación futura con respecto a las pestañas, que reducirá presumiblemente la brecha existente con respecto a la investigación sobre el cuero cabelludo

On the correlation between the curvature of the human eyelash and its geometrical features.

Although human eyelashes are generally curved, the cause of the natural curvature of eyelashes has not yet to be clarified elsewhere. Related with this, this paper reports our discovery of a correlation between the curvature of the eyelash and its geometrical features. Eyelashes can be divided into root, middle and tip sections. Because the curvature at the root is larger than that at the tip, we expected that the root section could be more easily deformed by bending compared with the tip section. However, the structural elasticity in bending, which is the flexural rigidity without depending on the external dimensions, at the root was found to be greater than that at the tip, contrary to our initial expectations. Next we examined the internal dimensions of cross sections of the eyelashes, and found that the thicknesses of the cuticle layer at the root were different for the convex and concave sides of the curved eyelash, although these were almost the same at the tip. Theoretical analysis of this variation in thickness of the outer cuticle layer shows that this displaces the neutral axis. Finally, we found that there is a good correlation between the displacement of the neutral axis and the curvature of the eyelash. STATEMENT OF SIGNIFICANCE: Why are human eyelashes naturally curved? To find a hint for this question, the mechanical and geometrical properties of human eyelash were investigated. Although the curvature at the root of the eyelash was larger than that at the tip, this was not related to the deformability of the eyelash by bending. From the cross-sectional observation of eyelash, we noticed that the thickness of the outer cuticle layer was non-uniform depending on the position, and this brought the displacement of the neutral axis of the eyelash for bending. Finally, a good correlation between the curvature and the change in the neutral axis was discovered. With practically using this findings, the curvature of the eyelash might be controlled artificially in the future.

The eyelash follicle features and anomalies: A review.

The primary role of eyelashes is to protect and maintain the health of the lid margin. However, the mechanisms to fulfill this role are not fully understood. Unraveling these mechanisms will stand to greatly improve the efficiency of eye care professionals' interventions in anomalies of the eyelashes. The aim of this article is to provide a review on eyelashes including highlights and new avenues for research; the biology of both the lash and its follicle; the pathophysiology and management of lash anomalies by eye care professionals; and the effect of iatrogenic factors on lashes. Using the database of Ovid MEDLINE, we reviewed studies specifically directed on human/mammalian eyelashes and key articles on current trends in scalp hair methodologies that can be applicable to lash research. The eyelash morphology, pigmentation and growth rate have been documented using techniques ranging from lash imaging to follicle immunohistochemistry. Furthermore, studies have demonstrated that the lash follicle is sensitive to many factors of the external environment, a variety of systemic/topical medications and cosmetics. Recently, aerodynamic studies using a mammalian eye model confirmed that an optimal lash length was needed so that eyelashes serve a protective role in reducing the number of particles that can reach the eye. Despite recent advances in lash research, studies are still scarce, due to the limited availability of the human lid for sampling. This review brings awareness that further research is needed with respect to eyelashes and will hopefully reduce the gap with scalp hair research.

Morphological criteria of feminine upper eyelashes, quantified by a new semi-automatized image analysis: Application to the objective assessment of mascaras.

BACKGROUND: The wide diversity of feminine eyelashes in shape, length, and curvature makes it a complex domain that remains to be quantified in vivo, together with their changes brought by application of mascaras that are visually assessed by women themselves or make-up experts. METHODS: A dedicated software was developed to semi-automatically extract and quantify, from digital images (frontal and lateral pictures), the major parameters of feminine eyelashes of Mexican and Caucasian women and to record the changes brought by the applications of various mascaras and their brushes, being self or professionally applied. RESULTS: The diversity of feminine eyelashes appears as a major influencing factor in the application of mascaras and their related results. Eight marketed mascaras and their respective brushes were tested and their quantitative profiles, in terms of coverage, morphology, or curvature were assessed. Standard applications by trained aestheticians led to higher and more homogeneous deposits of mascara, as compared to those resulting from self-applications. CONCLUSION: The developed software appears a precious tool for both quantifying the major characteristics of eyelashes and assessing the making-up results brought by mascaras and their associated brushes.

Topical medication instillation techniques for glaucoma.

BACKGROUND: Glaucoma is a leading cause of irreversible blindness worldwide and the second most common cause of blindness after cataracts. The primary treatment for glaucoma aims to lower intraocular pressure (IOP) with the use of topical medicines. Topical medication instillation techniques, such as eyelid closure and nasolacrimal occlusion when instilling drops, have been proposed as potential methods to increase ocular absorption and decrease systemic absorption of the drops. OBJECTIVES: To investigate the effectiveness of topical medication instillation techniques compared with usual care or another method of instillation of topical medication in the management of glaucoma or ocular hypertension. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 12), MEDLINE Ovid (1946 to 8 December 2016), Embase Ovid (1947 to 8 December 2016), PubMed (1948 to 8 December 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 8 December 2016), International Pharmaceutical Abstracts Database (1970 to 8 December 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (last searched 13 May 2013), ClinicalTrials.gov (www.clinicaltrials.gov) (searched 8 December 2016) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en) (searched 8 December 2016). We did not use any date or language restrictions in the electronic searches for trials. SELECTION CRITERIA: We included randomized controlled trials which had compared any topical medication instillation technique with usual care or a different method of instillation of topical medication. DATA COLLECTION AND ANALYSIS: Two review authors independently screened records from the searches for eligibility, assessed the risk of bias, and extracted data. We followed methods recommended by Cochrane. MAIN RESULTS: We identified two trials (122 eyes of 61 participants) that had evaluated a topical medication instillation technique. We also identified two ongoing trials. Both included trials used a within-person design and administered prostaglandin monotherapy for glaucoma or ocular hypertension. Because the trials evaluated different instillation techniques and assessed different outcomes, we performed no meta-analysis.One trial, conducted in the US, evaluated the effect of eyelid closure (one and three minutes) versus no eyelid closure on lowering IOP. At one to two weeks' follow-up, reduction in IOP was similar in the eyelid closure group and the no eyelid closure group (mean difference (MD) -0.33 mmHg, 95% confidence interval (CI) -0.8 to 1.5; 51 participants; moderate-certainty evidence).The second trial, conducted in Italy, evaluated the effect of using an absorbent cloth to wipe excess fluid after instillation (fluid removal) versus not using an absorbent cloth (no removal) on reducing dermatologic adverse events. At four months' follow-up, eyelashes were shorter among eyes in the fluid removal group compared with the no fluid removal group (MD -1.70 mm, 95% CI -3.46 to 0.06; 10 participants; low-certainty evidence). Fewer eyes showed skin hyperpigmentation in the eyelid region towards the nose in the fluid removal group compared with the no removal group (RR 0.07, 95% CI 0.01 to 0.84; 10 participants; low-certainty evidence); however, the difference was uncertain in the eyelid region towards the temples (RR 0.44, 95% CI 0.07 to 2.66; 10 participants; low-certainty evidence). The effect hypertrichosis (excessive hair growth) was uncertain between groups (RR 1.00, 95% CI 0.17 to 5.98; 10 participants; low-certainty evidence).Neither trial reported other outcomes specified for this review, including the proportion of participants with IOP less than 21 mmHg; participant-reported outcomes related to the ease, convenience, and comfort of instillation techniques; physiologic measurements of systemic absorption; escalation of therapy; mean change in visual fields; optic nerve progression; mean change in best-corrected visual acuity; proportion in whom glaucoma developed; quality of life outcomes; or cost-effectiveness outcomes. Neither trial reported data at follow-up times of more than four months. AUTHORS' CONCLUSIONS: Evidence to evaluate the effectiveness of topical medication instillation techniques for treatment of glaucoma is lacking. It is unclear what, if any, effects instillation techniques have on topical medical therapy for glaucoma.

Biology of the eyelash hair follicle: an enigma in plain sight.

Because of their crucial impact on our perception of beauty, eyelashes constitute a prime target for the cosmetic industry. However, when compared with other hair shafts and the mini-organs that produce them [eyelash hair follicles (ELHFs)], knowledge on the biology underlying growth and pigmentation of eyelashes is still rudimentary. This is due in part to the extremely restricted availability of human ELHFs for experimental study, underappreciation of their important sensory and protective functions and insufficient interest in understanding why they are distinct from scalp hair follicles (HFs) (e.g. ELHFs produce shorter hair shafts, do not possess an arrector pili muscle, have a shorter hair cycle and undergo greying significantly later than scalp HFs). Here we synthesize the limited current knowledge on the biology of ELHFs, in humans and other species, their role in health and disease, the known similarities with and differences from other HF populations, and their intrinsic interethnic variations. We define major open questions in the biology of these intriguing mini-organs and conclude by proposing future research directions. These include dissecting the molecular and cellular mechanisms that underlie trichomegaly and the development of in vitro models in order to interrogate the distinct molecular controls of ELHF growth, cycling and pigmentation and to probe novel strategies for the therapeutic and cosmetic manipulation of ELHFs beyond prostaglandin receptor stimulation.

Nuevas teorías sobre la función de las pestañas. ¿Una cuarta capa en la película lacrimal? / New theories on the role of the eyelashes. A fourth layer in the tear film?

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Characterization of Normal Mediolateral Angular Direction of Lower Eyelid Eyelashes in Different Age Groups.

PURPOSE: To characterize the normal eyelash mediolateral angular direction of the lower eyelid in different age groups. METHODS: Sixty patients were divided into 3 groups: G1 - 6 to 12 years; G2 - 20 to 35; and G3 - 60 to 85. Digital photographs were obtained and eyelids were divided in lateral, central, and medial portions. Eyelash mediolateral angular direction relative to a baseline was measured and data were compared between portions and groups. RESULTS: The mean eyelash mediolateral angular direction in the medial portion were: G1: 133.79° ± 17.56° SD; G2: 137.74° ± 10.5° SD; and G3: 116.05° ± 26.71° SD. The mean difference in angle between G1 and G3 was 17.74° (p = 0.015) and between G2 and G3 was 21.69° (p = 0.000). The mean eyelash mediolateral angular direction in central portion were: G1: 64.36° ± 12.58° SD; G2: 77.07° ± 12.17° SD; and G3: 84.9° ± 18.48° SD. The mean difference between Group 1 and 2 was 12.71° (p = 0.001) and between Group 1 and 3 was 20.54° (p = 0.000). The mean eyelash mediolateral angular direction in the lateral portion were: Group 1: 40.57° ± 6.78° SD; Group 2: 37.21° ± 5.69° SD; and Group 3: 38.48° ± 8.35° SD. CONCLUSION: This study identified that lashes in the lateral portion of lower eyelid tend to maintain the same angular position throughout life. On the central and medial portions it tends to approach a 90° angle with age. The authors believe that this modification throughout life may be related to factors, such as involutional horizontal eyelid laxity and orbicular muscle modifications.

Epidemiologic analysis of change in eyelash characteristics with increasing age in a population of healthy women.

BACKGROUND: Observations that eyelashes become thinner, shorter, and lighter, as women age has not been previously quantified. OBJECTIVE: This study was conducted to investigate associations between eyelash characteristics and age. MATERIALS AND METHODS: The upper natural eyelashes of 179 subjects were photographed and analyzed (digital image analysis); length, thickness, and darkness (intensity: 0 = white and 255 = black) were calculated. Linear regression, including race as a potentially confounding factor, was used to assess the association between age and mean eyelash characteristics. RESULTS: Subjects' mean age was 40.3 (±10.3) years; 46.1% were white, 36.5% Asian, 9.0% Hispanic, 5.1% East Indian, and 3.4% black. Mean eyelash length ranged from 6.39 (±1.02) to 7.98 (±1.15) mm (subjects aged 50-65 years and 22-29 years, respectively). Mean thickness ranged from 1.17 (±0.42) to 1.62 (±0.56) mm (subjects aged 50-65 years and 20-29 years, respectively). Mean intensity ranged from 118.2 (±19.8) to 129.4 (±17.3) (subjects aged 30-39 years and 50-65 years, respectively). Adjusted for race, eyelash length, thickness, and darkness decreased significantly with increasing age (p < .000, p = .0090, and p < .05, respectively). CONCLUSION: Advancing age among an ethnically diverse population of healthy women is associated with significant decreases in eyelash length, thickness, and darkness.

Adjunctive skin care of the brow and periorbital region.

This article discusses adjunctive skin care of the brow and periorbital region. Anatomic properties of eyelid skin require skin care products specifically suited to this area. Common patient concerns, including wrinkles, infraorbital dark circles, puffiness, and thinning eyebrows and eyelashes, are addressed in the context of contributing anatomic and physiologic factors and the classes of and/or specific ingredients targeting these problems.

Human eyelash characterization.

BACKGROUND: Few biological data on human eyelash follicles have been reported in the literature. OBJECTIVES: To characterize eyelash follicle growth, cycle and morphology, and further investigate the biological mechanisms that determine eyelash length, curl and pigmentation, compared with scalp hair follicle. METHODS: Twenty-nine caucasian female volunteers aged between 26 and 60 years were enrolled in the study to provide eyelashes. Four of these volunteers were followed weekly for 9 months to characterize their eyelash cycle. Eyelash length and time of renewal were measured using a high-resolution camera and image analysis. Immunohistological study of the bulbs were performed on eyelid biopsies from 17 patients requiring block excision for ectropion repair. RESULTS: The calculated durations of anagen phase and complete cycle of the eyelashes were 34 + or - 9 and 90 + or - 5 days, respectively. Eyelash follicle growth rate was quite variable, with an average rate of 0.12 + or - 0.05 mm daily. Eyelash follicle morphology was very close to that of the scalp hair follicle, but some remarkable differences were noticed. For example, the K19-positive epithelial stem cell population was spread all along the follicle and not split into two reservoirs as seen in scalp hair follicles. Some asymmetry was detected in HSPG and CSPG, as well as K38 (formerly Ha8) and K82 (formerly Hb2) distribution, similar to that observed in curly hair. Finally, dopachrome tautomerase was found expressed in eyelash follicle melanocytes, while it was strikingly absent in scalp hair follicle melanocytes. CONCLUSIONS: The eyelash is structurally very close to curly hair but some biological processes related to follicle cycle and pigmentation differ markedly.

Elements of morphology: standard terminology for the periorbital region.

An international group of clinicians working in the field of dysmorphology has initiated the standardization of terms used to describe human morphology. The goals are to standardize these terms and reach consensus regarding their definitions. In this way, we will increase the utility of descriptions of the human phenotype and facilitate reliable comparisons of findings among patients. Discussions with other workers in dysmorphology and related fields, such as developmental biology and molecular genetics, will become more precise. Here we introduce the anatomy of the periorbital area and define and illustrate the terms that describe the major characteristics of the periorbital area.

An improved method for Daugman's iris localization algorithm.

Computer-based automatic recognition of persons for security reasons is highly desirable. Iris patterns provide an opportunity for separation of individuals to an extent that would avoid false positives and negatives. The current standard for this science is Daugman's iris localization algorithm. Part of the time required for analysis and comparison with other images relates to eyelid and eyelash positioning and length. We sought to remove the upper and lower eyelids and eyelashes to determine if separation of individuals could still be attained. Our experiments suggest separation can be achieved as effectively and more quickly by removing distracting and variable features while retaining enough stable factors in the iris to enable accurate identification.

Ethnic characteristics of eyelashes: a comparative analysis in Asian and Caucasian females.

BACKGROUND: Despite similar biochemical composition of human hair between races, physico-morphological characteristics are not identical in different ethnic groups. Eyelashes have been investigated far less than scalp hair, and the information available is insufficient. OBJECTIVES: To obtain basic information about eyelashes and to clarify differences between female eyelashes in Asians and Caucasians. METHODS: Twenty Asian and 10 white Caucasian female volunteers aged between 20 and 29 years were admitted to the study. Lateral digital photographs of upper eyelashes were taken and curl-up and lift-up angles of upper eyelashes were measured from lateral views. Images of upper eyelashes were also taken using the phototrichogram technique and total numbers, lengths and thicknesses of upper eyelashes were obtained (a total of 4661 eyelashes; 2946 for Asian, 1715 for Caucasian). The central portion of the eyelashes or whole eyelashes were clipped and images were taken immediately and 7 days later to obtain the growth rate and anagen ratio of upper eyelashes. Numbers and thickness of eyelash cuticular layers were obtained by electron microscopy. RESULTS: Compared with Caucasians, Asian eyelashes revealed lower lift-up and curl-up angles, fewer numbers and a thicker transverse diameter. However, no statistical difference was observed in length or growth rate. Duration of anagen was estimated at about 2 months. The eyelash anagen ratio obtained from five Asians was 17.8 +/- 3.3%. By electron microscopy, the number of cuticular layers in transverse section was greater in Asian (8.0 +/- 1.2) than Caucasian females (6.5 +/- 1.1), but no statistical difference was found in single cuticle layer thickness between the two groups. Moreover, eyelash characteristics were not influenced by eye makeup in either race. CONCLUSIONS: Our results on eyelash morphology and growth characteristics demonstrated significant ethnic differences in Asian and Caucasian females that could provide basic information for future investigations.

Thickness of Korean upper eyelid skin at different levels.

This study aims at elucidating the thickness of the Korean upper eyelid at different levels. Left eyelids of 10 (9 males and 1 female) fresh Korean cadavers were dissected. Full thickness upper eyelids were cut and trichrome stained. The thickness was measured under a microscope.The thickness of upper eyelid skin varied at different levels. The thickest part of the upper eyelid is just below the eyebrow (D) (1.127 +/- 238 microm), and the thinnest skin is near the ciliary margin (A) (320 +/- 49 microm). The upper tarsal area (C) and mid tarsal area (B) are 832 +/- 213 and 703 +/- 103 microm, respectively. "A" area was significantly thinner than mid tarsal "B" area (P = 0.000). The skin above the tarsus was thicker than the "B" area, but there was no significant difference (P = 0.081). The skin just below the eyebrow, "D," was thicker than the upper tarsal border, "C" area (P = 0.011). The epidermis accounted for 11.2% of the entire skin near the ciliary margin. However, epidermis presented less (4.2-5.5%) of the whole skin at other levels (P = 0.000). The distance between ciliary margin and the point where the skin turns suddenly thicker was 1.89 +/- 0.23 mm. The size of the tarsal plate was 8.88 +/- 0.81 mm. These data of upper eyelid skin thickness may apply to Asian double fold surgery and also to full thickness skin donation for grafting.