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Eyelashes are important anatomical structures that protect the eye by stopping the particulate matter from getting to the eye and also by diverting water and wind. Lashes also have a strong sensory innervation making them capable of detecting noxious agents with appropriate protective responses by the eyelids and the periorbital muscles. A large number of congenital and acquired diseases and conditions can affect eyelashes. It is important to identify the cause where possible and recognize how the lashes behave differently from the normal before corrective measures are undertaken. A comprehensive overview of all diseases and conditions that directly affect eyelashes is presented. This activity reviews the evaluation and management of diseases of the eyelid and the role of interprofessional team members in collaborating to provide well-coordinated care and enhance patient outcomes. Objectives: Review the cause of trichiasis. Explain the treatment and management of trichiasis. Summarize the different types of eyelash disorders. Outline the evaluation and management of diseases of the eyelid and the role of interprofessional team members in collaborating to provide well-coordinated care and enhance patient outcomes. Access free multiple choice questions on this topic.

Eyelashes are important anatomical structures that protect the eye by preventing particulate matter from reaching it and by diverting water and wind.[1] Lashes also have a strong sensory innervation, enabling them to detect noxious agents and elicit appropriate protective responses from the eyelids and periorbital muscles. A large number of congenital and acquired diseases and conditions can affect eyelashes. It is important to identify the cause, where possible, and to understand how the lashes behave differently from normal lashes before corrective measures are undertaken. A comprehensive overview of all diseases and conditions that directly affect eyelashes is presented. See Image. Anatomical Structures, Eyelashes.

Trichiasis Trichiasis is defined as normal lashes growing inward. In trichiasis, the lash follicle is normal, but the direction of lash growth is abnormal. In the presence of inflammation, there may be a misdirection of the follicle with the lash growing inwards towards the cornea, but the cause is not entropion. Some authors have divided trichiasis into primary, where the lash is misdirected by the abnormal direction of the shaft of the hair, and secondary trichiasis, where there is a misdirection of the follicle. We have found this division less useful in clinical practice. Others have classified trichiasis as minor (fewer than 5 cilia) and major (more than 5 cilia). Mostly, trichiasis affects the lower eyelid. See Image. Eye Disorders and Trachoma-Associated Symptoms, Trichiasis. Examination under the biomicroscope should assess the lid margin, the posterior lamella, and the fornices (looking for symblepharon or scarring). An examination reveals lashes pointing backward, rubbing against the conjunctiva or the cornea. The lashes may be in their normal position, or may be growing from behind the normal eyelashes. Scarring of the eyelid margin secondary to inflammation should be looked for. Trichiasis is differentiated from involutional entropion, where the eyelid margin turns in and causes normal lashes to rub against the cornea. This is often termed secondary trichiasis or pseudo-trichiasis.[2] Causes Chronic blepharitis Vernal keratoconjunctivitis Chemical burns Thermal injury Eczema Herpes zoster Atopic diseases Ocular cicatricial pemphigoid disease Cicatrizing conjunctival disease Eyelid trauma Eyelid surgery Meibomitis Stevens-Johnson syndrome Leprosy Eyelid tumors Trachoma Chalazia: Sometimes one see trichiasis at a site of a prior chalazion, which may or may not have been surgically drained: the collapsed meibomian gland can cause a local change in the architecture, with lashes turning in. Mostly, trichiasis affects the lower eyelid, except in chemical burns (where both lids are affected) or trachoma, where the upper eyelid is more severely affected (see Image. Trichiasis). Chlamydia trachomatis causes trachoma, a disease endemic in sub-Saharan Africa. In trachoma, inflammation of the eyelid margin and conjunctiva can cause a combination of trichiasis and cicatricial entropion. Corneal scarring and eventual corneal opacification can occur.[3] Management

Mostly, trichiasis affects the lower eyelid, except in chemical burns (where both lids are affected) or trachoma, where the upper eyelid is more severely affected (see Image. Trichiasis). Chlamydia trachomatis causes trachoma, a disease endemic in sub-Saharan Africa. In trachoma, inflammation of the eyelid margin and conjunctiva can cause a combination of trichiasis and cicatricial entropion. Corneal scarring and eventual corneal opacification can occur.[3] Management Short-term relief may be obtained by epilating the lashes or inserting a bandage contact lens. Surgical treatment should only be undertaken after active inflammation is brought under control. Permanent destruction of the roots of the offending lashes is achieved using numerous techniques, including argon laser, electrolysis, radiofrequency epilation, trephination, eyelash bulb extirpation, resection of the lash follicle, cryotherapy, and surgical repositioning. We use the radiofrequency needle to the depth of the root of the lashes (2.4 mm deep in the upper lid and 1.4 mm in the lower lid) to kill the offending lash roots. Monopolar electrocautery is used less often now as it causes more collateral thermal injury to the eyelid margin. Distichiasis Distichiasis is defined as a separate row of lashes that is present behind the normal row of lashes. These lashes are fine but have little pigmentation and cause corneal irritation. Various forms of distichiasis are seen, from a complete row of lashes to an irregular row. Distichiasis may be congenital, in which case the pilosebaceous units differentiate into lashes instead of meibomian glands. In the autosomal lymphedema-distichiasis syndrome, distichiasis is associated with limb lymphedema, and there may be cleft palate and cardiac abnormalities.[4] Other congenital causes of distichiasis include mandibulofacial dystonia and Setleis syndrome (focal facial dermal dysplasia with upper eyelid lashes present in multiple rows or eyelashes may be completely absent).

Distichiasis is defined as a separate row of lashes that is present behind the normal row of lashes. These lashes are fine but have little pigmentation and cause corneal irritation. Various forms of distichiasis are seen, from a complete row of lashes to an irregular row. Distichiasis may be congenital, in which case the pilosebaceous units differentiate into lashes instead of meibomian glands. In the autosomal lymphedema-distichiasis syndrome, distichiasis is associated with limb lymphedema, and there may be cleft palate and cardiac abnormalities.[4] Other congenital causes of distichiasis include mandibulofacial dystonia and Setleis syndrome (focal facial dermal dysplasia with upper eyelid lashes present in multiple rows or eyelashes may be completely absent). Secondary distichiasis is seen in conditions that cause inflammation, which in turn leads to metaplasia of the Meibomian glands, forming lashes within the Meibomian glands (see Image. Congenital Distichiasis). These conditions are similar to those that cause trichiasis, including blepharitis, caustic injuries, meibomian gland dysfunction, meibomitis, ocular cicatricial pemphigoid, and Stevens-Johnson syndrome.[4] Management This includes epilation, cryotherapy, trephination, folliculectomy, lid split, treatment of abnormal follicles, and radiofrequency treatment of the follicles. In acquired distichiasis, eyelid inflammation may occur (Meibomian gland dysfunction, cicatricial pemphigoid, Stevens-Johnson syndrome). Inflammation induces metaplasia of the Meibomian glands, forming lashes within them. There may be a need to apply a mucous membrane graft, particularly if there is mucocutaneous keratinization. Tristichia/Tetrastichiasis The presence of a third row of lashes. Tetrastichiasis is the presence of a fourth row of lashes. These are rare conditions. Pseudocilium Sometimes, an eyelash can be seen in a meibomian gland orifice or the punctum. We have termed this "pseudocilium" because the lash does not have a root but is loose in the meibomian gland or the punctum. Such an isolated lash can find its way into a meibomian gland or punctum still and may have the tip of the lash on the outside or the root on the outside (upside-down lash). Either way, the lash can still cause corneal and conjunctival irritation. Treatment is simply the removal of the lash from the orifice of the meibomian gland or the punctum.

Sometimes, an eyelash can be seen in a meibomian gland orifice or the punctum. We have termed this "pseudocilium" because the lash does not have a root but is loose in the meibomian gland or the punctum. Such an isolated lash can find its way into a meibomian gland or punctum still and may have the tip of the lash on the outside or the root on the outside (upside-down lash). Either way, the lash can still cause corneal and conjunctival irritation. Treatment is simply the removal of the lash from the orifice of the meibomian gland or the punctum. Hypotrichosis Hypotrichosis, which is defined as reduced hair density anywhere in the body, may also affect eyelashes. The only effective treatment is topical bimatoprost ophthalmic solution 0.03%. It is applied to the lash base, resulting in thicker, longer, and darker lashes. Bimatoprost is thought to prolong the anagen phase of the lash cycle. Results are seen in 16 weeks. A recent concern is that some patients may experience orbital fat atrophy after prolonged use of a topical bimatoprost solution. Side effects include increased iris and skin pigmentation and skin irritation, all of which reverse upon discontinuation of the medication. Alopecia Adnata has been used to describe underdeveloped eyelashes. Alopecia areata, which is thought to be an autoimmune process, can also affect eyelashes. See Image. Alopecia Areata With Eyelash Loss. Madarosis Madarosis is the loss of lashes (ciliary madarosis) or eyebrows (superciliary madarosis). Milphosis means eyelash loss. Madarosis and milphosis are often used interchangeably. Trichotillomania is the self-induced pulling of hair from anywhere on the body, but it also includes eyelash-pulling. In most cases, psychiatric evaluation and treatment are needed.[5] Causes Blepharitis Meibomian gland dysfunction Ocular rosacea Seborrheic blepharitis Staphylococcal infection Demodex infestation Trachoma Congenital syndromes like Oliver-McFarlane and Cornelia de Lange Alopecia Universalis is a type of alopecia that also results in loss of lashes. In this condition, corticosteroids and topical immunotherapy have been used successfully to achieve hair growth. T-cell lymphoma and associated follicular mucinosis Allergic contact dermatitis may be caused by many cosmetics and ophthalmic medications with preservatives and other chemicals.

Alopecia Universalis is a type of alopecia that also results in loss of lashes. In this condition, corticosteroids and topical immunotherapy have been used successfully to achieve hair growth. T-cell lymphoma and associated follicular mucinosis Allergic contact dermatitis may be caused by many cosmetics and ophthalmic medications with preservatives and other chemicals. Superficial inflammation from any cause can lead to irritation and rubbing of the brows and lashes with pigmentation, skin laxity, and lash loss. Psoriasis Atopic dermatitis, which may be associated with allergic rhinitis, keratoconjunctivitis, and vernal conjunctivitis, causes loss of lashes on the lateral third of the brows (termed Hertoghe sign). Acne rosacea results in blepharitis, keratitis, and telangiectatic changes on the cheeks and nose Alopecia areata may result in patchy loss of lashes. The lashes have an “exclamation mark” configuration of broken hairs: this is pathognomonic of this disease. Discoid lupus erythematosus and systemic lupus erythematosus: chronic blepharoconjunctivitis and madarosis may occur. Scleroderma en coup de sabre, which is localized scleroderma, shows a segmental loss of eyebrows and lashes Hypothyroidism may cause brittle hairs mostly affecting the brows, but also lashes Hyperthyroidism may cause ciliary madarosis Malignancy: basal cell carcinoma, squamous cell carcinoma, Merkel cell carcinoma, mycosis fungoides (cutaneous T-cell lymphoma), sebaceous cell carcinoma. Recalcitrant dermatitis and chronic blepharoconjunctivitis or recurrent chalazia should be indications for biopsy of the eyelid and eyelid margin. Chemotherapy Herpes zoster is a common cause of madarosis of the upper or lower eyelid. Secondary syphilis can cause eyebrow loss and eyelash loss. Leprosy as a cause is seen less frequently now. HIV/AIDS may cause madarosis or trichomegaly. Drugs: Systemic drug toxicity and local topical agents may cause madarosis. Trauma: Eyelid lacerations, chemical and thermal injuries, and tattooing can all cause madarosis. Trichotillomania is a condition in which patients pull hair (scalp being the most common, followed by eyelashes). As these are episodic, may be confused with alopecia areata. A biomicroscopic examination reveals broken hairs of varying lengths, with no underlying skin condition. Trichotemnomania is a loss of hair by repeated rubbing, and trichotemnomania is a loss by obsessive shaving.

Trichotillomania is a condition in which patients pull hair (scalp being the most common, followed by eyelashes). As these are episodic, may be confused with alopecia areata. A biomicroscopic examination reveals broken hairs of varying lengths, with no underlying skin condition. Trichotemnomania is a loss of hair by repeated rubbing, and trichotemnomania is a loss by obsessive shaving. Congenital diseases: numerous diseases are associated with hair loss, including ectodermal dysplasias, Ichthyosis-cheek-eyebrow syndrome, localized autosomal recessive hypotrichosis, and Rothmund-Thompson syndrome. Management Given such a disparate list of causes of eyelash madarosis, the underlying condition must be diagnosed and treated. Eyebrow transplants may be used for superciliary madarosis. Eyelash transplants have not gained popular acceptance because of the risk of trichiasis and lack of lifelike hair on the lid margin. A successful take is not predictable (depending upon the underlying disease and condition of the eyelid). Composite eyebrow grafts may be used to reconstruct eyelids with segmental eyelash loss. Hypertrichosis is an increase in hair in any area of the body, taking the patient’s age, gender, and ethnicity into consideration. Eyelash hypertrichosis is known as trichomegaly.[6] As with madarosis, the list of diseases associated with hypertrichosis and trichomegaly is long: Congenital hypertrichosis lanuginosa and generalized hypertrichosis cause increased hair on the body and eyelashes. Neurofibroma Cornelia de Lange syndrome Goldstein Hutt syndrome Phenylketonuria Type I oculocutaneous albinism Tyrosinemia Eyebrow Hypertrichosis is seen in: Coffin-Siris syndrome Gingival fibromatosis with hypertrichosis Hermansky-Pudiak syndrome Mannosidosis Nevoid hypertrichosis (isolated area of hypertrichosis) Stiff skin syndrome Langer-Giedion syndrome Duplication of supercilia (2 distinct brows) Mucopolysaccharidoses Rubenstein-Taybi syndrome Cornelia de Lange syndrome Acquired Hypertrichosis (Hypertrichosis lanuginosa acquisita [HLA]) Drugs Metabolic diseases Endocrine diseases Paraneoplastic processes: patients may develop increased lanugo hairs in the periocular, ear, forehead, and nose areas. In paraneoplastic processes, hypertrichosis may develop before malignancy is recognized.

Cornelia de Lange syndrome Acquired Hypertrichosis (Hypertrichosis lanuginosa acquisita [HLA]) Drugs Metabolic diseases Endocrine diseases Paraneoplastic processes: patients may develop increased lanugo hairs in the periocular, ear, forehead, and nose areas. In paraneoplastic processes, hypertrichosis may develop before malignancy is recognized. Lawrence-Seip syndrome is characterized by lipoatrophy, resulting in hypertrichosis of the head, with involvement of the forehead, eyebrows, eyelashes, and cheeks.[7] Trichomegaly (increased eyelash and/or eyebrow length) Anorexia nervosa Atopic dermatitis Allergic rhinitis (results in long, smooth lashes) Dermatomyositis Hypothyroidism Malnutrition Pregnancy Hypothyroidism Porphyria Systemic lupus erythematosus Linear scleroderma Vernal keratoconjunctivitis Uveitis Voght Koyanagi Harada syndrome HIV/AIDS may cause trichomegaly as well as madarosis Many drugs have been associated with trichomegaly, causing thickening and even curling. The common ones are prostaglandin analogs used to treat glaucoma (eg, latanoprost, bimatoprost), epithelial growth factor receptor tyrosine kinase inhibitors, cyclosporine, topiramate, tacrolimus, and interferon-alpha. Cone-rod dystrophy Goldstein Hutt syndrome Kabuki makeup syndrome Olver-Macfarlane syndrome Phenylketonuria Type I oculocutaneous albinism Tyrosinemia Management Treatment is similar to that outlined under trichiasis if there is eye irritation or associated trichiasis. Synophrys is commonly referred to as a “unibrow” or "monobrow." Synophrys is seen in centrofacial lentiginosis, cretinism, Sup (3q) syndrome, fetal trimethadione syndrome, Hajdu-Cheney syndrome, and Waardenburg syndrome. Laser hair removal may be used to separate the brows.[8] Cilia  Incarnata Cilia Incarnata is a term used to describe an eyelash that burrows under the skin to either the surface (cilium incarnatum externum) or posteriorly through the tarsal conjunctiva (cilium incarnatum internum). These conditions are discussed in detail elsewhere. The eyelash root is normal; just the direction of growth of the shaft of the lash is abnormal. A patient with cilia incarnata internum presents a history of irritation of the eye with localized punctate keratopathy, and a patient with cilia incarnata externum may present asymptomatically or with a complaint of "a bump." Both conditions are diagnosed by examining under the biomicroscope. Simple removal of the lash is almost always curative. Eyelash Ptosis

Cilia Incarnata is a term used to describe an eyelash that burrows under the skin to either the surface (cilium incarnatum externum) or posteriorly through the tarsal conjunctiva (cilium incarnatum internum). These conditions are discussed in detail elsewhere. The eyelash root is normal; just the direction of growth of the shaft of the lash is abnormal. A patient with cilia incarnata internum presents a history of irritation of the eye with localized punctate keratopathy, and a patient with cilia incarnata externum may present asymptomatically or with a complaint of "a bump." Both conditions are diagnosed by examining under the biomicroscope. Simple removal of the lash is almost always curative. Eyelash Ptosis Eyelash ptosis is defined as a downward curve or bend to the upper eyelid lashes. Normal upper eyelashes have an upward curve. A normal eyelash curve, bend, and position are determined by the underlying integrity of the orbicularis oculi muscle, the Riolan muscle, which is part of the orbicularis oculi muscle at the eyelid margin, and the tarsal plate and elastin. If any of these structures are affected by trauma or disease, eyelash ptosis can occur. The most common medical condition associated with eyelash ptosis is Floppy Eyelid Syndrome (FES), in which the tarsal plate, orbicularis muscle, and eyelid elastin are all affected. The findings are almost always asymmetric, as the side the patient sleeps on shows more pronounced eyelid floppiness and eyelash ptosis. Patients present with red, irritated eyes; mucoid discharge from the eyes, worse in the mornings; papillary conjunctival inflammation; sleep apnea; and a history of weight gain (and loss).[9] The most common non-medical cause of eyelash ptosis is seen in patients using prostaglandin analogs for glaucoma, which also results in trichomegaly. Other conditions associated with eyelash ptosis are: Ptosis, congenital and acquired Leprosy Facial nerve palsy Dermatochalasis with anterior lamellar slide. Lower Eyelid Lash Ptosis (upward slant to lashes) Epiblepharon is the commonest cause. This is commonly seen in Asian races. A medial lower eyelid fold of skin and orbicularis is found, making the medial lashes turn upward, which may be termed lower eyelid lash ptosis. Although many patients show regression with age, some patients require a modified Hotz procedure to evert the medial lower eyelid.

Epiblepharon is the commonest cause. This is commonly seen in Asian races. A medial lower eyelid fold of skin and orbicularis is found, making the medial lashes turn upward, which may be termed lower eyelid lash ptosis. Although many patients show regression with age, some patients require a modified Hotz procedure to evert the medial lower eyelid. Thyroid orbitopathy, although this is more of a mechanical malposition caused by surrounding structures (the orbicularis in epiblepharon and proptosis and periorbital edema in thyroid orbitopathy). Management Treatment depends upon the cause. We tell all patients with the floppy eyelid syndrome that a permanent cure is defined as long-term weight loss. Indeed, we have seen impressive improvements without surgical treatment when a patient successfully loses and maintains the weight loss. Although the use of shields and lubricants can help, the definitive “cure” is for the patient to lose weight. Surgical resection of redundant rubbery upper and lower eyelids in a full-thickness manner is reserved for recalcitrant cases, with the proviso that this does not cure the condition and merely helps to create a firmer eyelid to protect the cornea. If there is continued weight gain and weight loss, together with “face sleeping,” the condition recurs. Also, the lashes often need to be trimmed because they tend to be long and downward-sloping. Cessation of prostaglandin analogs causes a reversal of the lash changes within a few months in patients with glaucoma drop-induced lash ptosis Cilium Inversum Cilium inversum, sometimes referred to as an “upside-down lash,” illustrates how the same clinical finding has been described under different names in the literature. The term was first reported in 1923 in the BMJ by Tibbles, followed by a publication by Schrieber in 1924. No further cases were described under this designation, as the condition termed cilium inversum is now recognized to represent the same entity as cilium incarnatum internum. The clinical features outlined in the early reports are consistent with what is currently classified under that diagnosis. Ectopic or Accessory Cilia

Cilium inversum, sometimes referred to as an “upside-down lash,” illustrates how the same clinical finding has been described under different names in the literature. The term was first reported in 1923 in the BMJ by Tibbles, followed by a publication by Schrieber in 1924. No further cases were described under this designation, as the condition termed cilium inversum is now recognized to represent the same entity as cilium incarnatum internum. The clinical features outlined in the early reports are consistent with what is currently classified under that diagnosis. Ectopic or Accessory Cilia Ectopic or accessory cilia are lashes that are found away from their normal location, which is the eyelid margin. Weigmann first described this in 1936. This condition is seen when the lashes grow through the tarsal plate and present in an area of the upper or lower eyelid, but the roots of the lashes are not at the eyelid margin. True ectopic cilia are seen congenitally. Traumatic ones are, of course, displaced cilia and are not true ectopic cilia. A positive family history of ectopic cilia may be obtained. With accessory cilia, histology reveals the presence of apocrine sweat glands attached to the follicle, which is necessary to diagnose the hairs as eyelashes. The lashes are managed with surgical resection or cryotherapy to permanently remove the offending lashes.[10] Buried Lash with Granuloma A granuloma may form around a broken lash, which embeds itself in the conjunctiva, causing local inflammation. This may be seen on the tarsal conjunctiva, or, more infrequently, in the forniceal conjunctiva. Simple removal of the lash is curative. Vellus Hair Cyst Eyelid/Orbit Sometimes, a vellus cyst may develop in the orbit and resemble an orbital tumor. Again, simple removal of the granuloma and offending lash is curative.[11] Poliosis Canities is the natural, gradual graying of hair shafts because of a decrease in tyrosine production in the hair bulb, whereas poliosis is the decrease or absence of pigment in hair anywhere on the body. It is caused by abnormalities in hair melanocytes or melanin in the hair follicles. Poliosis is seen in many conditions: Piebaldism Conjunctival melanoma Vitiligo Sarcoidosis Inflammatory systemic diseases Blepharitis Vernal keratoconjunctivitis Topical prostaglandin analogs Medications like chloramphenicol, cyclosporin A, and chloroquine. Oculocutaneous albinism manifests with fair lashes

Canities is the natural, gradual graying of hair shafts because of a decrease in tyrosine production in the hair bulb, whereas poliosis is the decrease or absence of pigment in hair anywhere on the body. It is caused by abnormalities in hair melanocytes or melanin in the hair follicles. Poliosis is seen in many conditions: Piebaldism Conjunctival melanoma Vitiligo Sarcoidosis Inflammatory systemic diseases Blepharitis Vernal keratoconjunctivitis Topical prostaglandin analogs Medications like chloramphenicol, cyclosporin A, and chloroquine. Oculocutaneous albinism manifests with fair lashes Griscelli syndrome (hypopigmentation of skin and hair with neurological deficits) Vogt-Koyanagi-Harada syndrome (uveitis, serous retinal detachment). Sympathetic ophthalmia Cicatricial pemphigoid Herpes zoster Irradiation Idiopathic uveitis Tuberous sclerosis Marfan syndrome Waardenburg syndrome (white forelock with scalp hair, eyebrow, and eyelash poliosis). A mycotic infection called white Piedra is caused by a yeast (Trichosporon), resulting in white nodules which may be mistaken for poliosis. This is treated with topical and systemic azoles. There is no medication available to restore lash pigmentation. Heterochromia is a rare condition characterized by differences in eyelash color between the right and left eyelashes. Abnormal Darkening of Lashes Abnormal darkening of eyelashes may be seen in type 2 diabetes and as a side effect of prostaglandin F2 alpha agents (which increase melanin production and melanocytes). Malformed Hair/ Brittle Hair Monilethrix (a rare autosomal dominant disease) and pili torti (which gives corkscrew hairs and involves eyebrows, lashes, temporal, and occipital scalp) cause brittle hair. Scurvy is caused by vitamin C deficiency, with corkscrew hairs, perifollicular hemorrhages, gingival hemorrhage, and fractured and bent hairs (swan-neck deformity). Menkes syndrome is a disorder of copper metabolism and a highly fatal condition. Hair shows “steel wool” quality and has seizures, hypotonia, and failure to thrive. Trichorrhexis  Invaginata is seen in Netherton syndrome, with atopic dermatitis and lichenification. Trichorrhexis invaginate refers to bamboo hair, in which the hair shaft has nodules along its length, which is pathognomonic for Netherton disease. Brow hair is affected, as is scalp hair. Benign Tumors of Hair Follicle Pilomatrixoma presents as a firm lesion with whitish nodules usually away from the eyelid margin.

Trichorrhexis  Invaginata is seen in Netherton syndrome, with atopic dermatitis and lichenification. Trichorrhexis invaginate refers to bamboo hair, in which the hair shaft has nodules along its length, which is pathognomonic for Netherton disease. Brow hair is affected, as is scalp hair. Benign Tumors of Hair Follicle Pilomatrixoma presents as a firm lesion with whitish nodules usually away from the eyelid margin. Trichoblastoma Trichilemmoma rarely affects the lid margin or canthus Trichoepithelioma Trichofolliculoma presents as a nodule with fine, white hair in the middle. Inverted Follicular Keratosis Malignant Tumors of Hair Follicle Primary mucinous carcinoma arises from eccrine sweat glands and presents as a nodule or ulcer. Infection of Hair Follicle Common bacteria naturally found on lashes include Propionibacterium, Streptophyta, Staphylococcus, Corynebacterium, and Enhydrobacter. In the presence of blepharitis, Staphylococcus, Streptophyta, Corynebacterium, and Enhydrobacter are increased. Propionibacterium, on the other hand, is often decreased in blepharitis. An infection of the gland of Zeis (sebaceous gland) and gland of Moll (apocrine gland) gives rise to a “stye,” also called an external hordeolum (as opposed to an internal hordeolum, which is a chalazion, or infection of the Meibomian gland within the tarsal plate). Infections along the eyelid margin have secondary effects on the hair follicles. Staphylococcal blepharitis results in crusts on lashes, squames or scales on the lid margins, telangiectatic vessels, and collarettes around lashes. There may be associated Meibomian gland dysfunction. In more chronic blepharitis, there may be madarosis, poliosis, tylosis, trichiasis, and eyelid margin irregularities. Lash Infestation

An infection of the gland of Zeis (sebaceous gland) and gland of Moll (apocrine gland) gives rise to a “stye,” also called an external hordeolum (as opposed to an internal hordeolum, which is a chalazion, or infection of the Meibomian gland within the tarsal plate). Infections along the eyelid margin have secondary effects on the hair follicles. Staphylococcal blepharitis results in crusts on lashes, squames or scales on the lid margins, telangiectatic vessels, and collarettes around lashes. There may be associated Meibomian gland dysfunction. In more chronic blepharitis, there may be madarosis, poliosis, tylosis, trichiasis, and eyelid margin irregularities. Lash Infestation Demodex folliculorum and Demodex brevis are parasites that are found on eyelashes.[12] Numbers increase with age, so that by age 70, almost 100% of people have these parasites. D. Folliculorum lives on hairs in brows, scalp, ears, and lashes. D. brevis is seen in Meibomian glands and sebaceous glands of the face. Demodex is an impressive parasite under magnification: it has a head, 4 pairs of legs, a body, and a tail that contains the digestive system and lacks an anus, so ingested material is eventually released when the parasite bursts. The parasite has a life cycle of 15 to 18 days. The released contents cause inflammation of the eyelid margin. With an increasing number of Demodex comes an increased incidence of blepharitis and demodicosis of the eyelid margin. Gelatinous debris is seen along the eyelid margin, and cylindrical dandruff around the lashes is pathognomonic of demodex. Pubic hair is infested with Phthirus pubis, which can be transmitted to eyelashes by hand and sexual transmission. This can result in Phthiriasis palpebrum: the parasite has brown scales that are actually its feces.[13] Nits are unhatched parasites that can be seen along the lid margin and fixed to the lashes. The patient develops irritation, itching, and inflammation of the eyelid margins. Management of Phthiriasis palpebrarum requires mechanical removal of the parasite and the nits. Iatrogenic Conditions

Demodex folliculorum and Demodex brevis are parasites that are found on eyelashes.[12] Numbers increase with age, so that by age 70, almost 100% of people have these parasites. D. Folliculorum lives on hairs in brows, scalp, ears, and lashes. D. brevis is seen in Meibomian glands and sebaceous glands of the face. Demodex is an impressive parasite under magnification: it has a head, 4 pairs of legs, a body, and a tail that contains the digestive system and lacks an anus, so ingested material is eventually released when the parasite bursts. The parasite has a life cycle of 15 to 18 days. The released contents cause inflammation of the eyelid margin. With an increasing number of Demodex comes an increased incidence of blepharitis and demodicosis of the eyelid margin. Gelatinous debris is seen along the eyelid margin, and cylindrical dandruff around the lashes is pathognomonic of demodex. Pubic hair is infested with Phthirus pubis, which can be transmitted to eyelashes by hand and sexual transmission. This can result in Phthiriasis palpebrum: the parasite has brown scales that are actually its feces.[13] Nits are unhatched parasites that can be seen along the lid margin and fixed to the lashes. The patient develops irritation, itching, and inflammation of the eyelid margins. Management of Phthiriasis palpebrarum requires mechanical removal of the parasite and the nits. Iatrogenic Conditions An explosion in periocular and periorbital aesthetics has led to lash tinting, the application of lash extensions with adhesives, eyelash and eyelid cosmetics, dyes, and sundry procedures and chemical use. Inevitably, contact dermatitis is on the rise, often caused by glues and lash-tinting dyes. Eyelid margin tattoos performed to enhance the appearance of the eyelashes can cause "leakage" of dye, necessitating laser treatments to reduce pigmentation. With tattoo inks being imported, allergic reactions are also being seen. Lash tinting uses dyes containing phenylenediamine, which are known to cause allergic dermatitis. Overuse of mascara can lead to lash cuticle cracking and also milphosis. Trauma

An explosion in periocular and periorbital aesthetics has led to lash tinting, the application of lash extensions with adhesives, eyelash and eyelid cosmetics, dyes, and sundry procedures and chemical use. Inevitably, contact dermatitis is on the rise, often caused by glues and lash-tinting dyes. Eyelid margin tattoos performed to enhance the appearance of the eyelashes can cause "leakage" of dye, necessitating laser treatments to reduce pigmentation. With tattoo inks being imported, allergic reactions are also being seen. Lash tinting uses dyes containing phenylenediamine, which are known to cause allergic dermatitis. Overuse of mascara can lead to lash cuticle cracking and also milphosis. Trauma A not uncommon injury to lashes is caused by inadvertent application of super glue (cyanoacrylate) into the eye when the tube is mistaken for an ocular ointment. These injuries have continued since 1982 when cyanoacrylate began to be sold in small tubes which resemble eye ointment tubes. Nail glue often comes in bottles that look like eye medication bottles. Most modern super glues harden immediately upon contact with moisture, which makes it impossible for the patient to open the eyelids. The eyelids and lashes are glued together. Although the eyelid margins may be stuck together, it is commonly the upper and lower eyelid lashes that are stuck. Warm soaks and irrigation help to loosen the glue on the lashes and eyelids, and can sometimes allow the eyelids to be prised open. However, it is often necessary to cut or trim the lashes to allow the lids to be opened. The eye should be examined for any hardened glue fragments, which should be removed after a topical anesthetic has been applied. The cornea should be examined for abrasions, and the standard corneal abrasion management should be undertaken. If there is partial adherence of the eyelids and the cornea can be examined to ensure there is no trauma, it is not unreasonable to prescribe topical ointment 3 times a day and warm soaks. This allows the super glue to soften over a few days, when the lids can be gently prised open with little cutting of lashes.

Eyelash conditions occur across all ages, genders, and ethnic subgroups. Infections (styes or external hordeola, which are infections of the lash roots) and Moll cysts are common in children and are self-limiting. They also become more common with age because of the increase in eyelid margin inflammation with blepharitis and increased Meibomian gland inflammation. Demodex infestation is normal and increases with age, so that by the age of 70 years, most adults have Demodex parasites on their lashes. Symptoms are much more common with age as the number of parasites increases. Trachoma is a preventable disease that causes blindness and afflicts the young in sub-Saharan Africa, caused by Chlamydia trachomatis. Person-to-person contact (often child-to-mother-to-child) is the primary mode of transmission, but it can also spread through flies and clothing. Unsanitary conditions predispose to the spread of this disease.

Trichiasis Trauma and inflammation distort the tissue around the lash root, causing the lash to grow in an abnormal direction, in this case, inwards towards the eye. The eyelid position is normal, although some cicatrizing diseases may cause an inward turn of the eyelid margin before progressing to frank cicatricial entropion. Distichiasis Metaplasia of the Meibomian glands results in the formation of lashes instead of the sebum-producing glands and may be seen congenitally or following eyelid inflammation. Madarosis Trauma, inflammation, or ischemia due to malignancy are involved in madarosis. The exact mechanism in conditions such as hyperthyroidism and hypothyroidism is not known. Trichomegaly When caused by drugs such as latanoprost and bimatoprost, the anagen phase of the lash cycle is prolonged, resulting in longer, thicker lashes. The same mechanism may be involved when trichomegaly is seen with other drugs. Cilia incarnata internum and externum In both these conditions, it is thought that the natural growth path of a lash is impeded, as the condition is almost always seen affecting a solitary lash. With the resistance, they may take the path of least resistance and grow outwards under the skin (externum) or through the tarsal plate and tarsal conjunctiva (internum). Eyelash Ptosis An abnormality in any of the structures that are responsible for the proper orientation of the lash follicle and shaft can result in eyelash ptosis. These structures are the pre-tarsal orbicularis oculi, Riolan muscle (which is the inferior part of the orbicularis oculi), the tarsal plate, and the elastin. All of these are affected in conditions such as floppy eyelid syndrome and facial paralysis, leading to lash ptosis. Poliosis Abnormalities of hair melanin in the follicles or hair melanocytes can cause poliosis. Demodex The number of normal parasites, Demodex folliculorum and Demodex brevis, increases with age, so that by age 70, almost everyone has these parasites. As their numbers increase, they cause more irritation, itching, and discomfort.

Most lash conditions are diagnosed by clinical examination; the relevant findings have been presented above. In the presence of trichiasis, a careful examination of the eyelid margin, the tarsal conjunctiva, the fornix, the bulbar conjunctiva, and the cornea is vital to exclude some of the more serious conditions that may initially present just with trichiasis. Trichiasis with Evidence of Lash Loss Examine the eyelid margin under the biomicroscope for vessels, ulceration, plaques, irregularities, which may indicate eyelid malignancy (basal cell carcinoma, squamous cell carcinoma). Trichiasis with Evidence of Lash Loss and Thickened Eyelid Beware the sebaceous carcinoma, which can present as a chalazion, vague lid thickening, loss of lashes, or trichiasis. Here, a full-thickness eyelid specimen is sent fresh to the pathologist for special stains and immunohistochemistry. Trichiasis with Conjunctival Scarring Examine the tarsal conjunctiva and the fornix for scarring and symblepharon. Trichiasis can be the first presentation of mucous membrane pemphigoid (MMP) disease. Trichiasis with Conjunctival Scarring, Entropion, Corneal Opacification Advanced stage trachoma presents with frank cicatricial entropion, corneal scarring, decreased vision, and conjunctival inflammation. The earlier stage of the disease shows follicular conjunctivitis with limbal follicles and limbal neovascularization. Madarosis Always examine the area of madarosis for underlying growth/thickening/ulceration/vascularization, which may be indicative of a malignancy.

If trichiasis is seen in the presence of conjunctival cicatricial changes and mucous membrane pemphigoid (MMP) disease is suspected, a conjunctival biopsy is obtained for direct immunofluorescence (DIF). However, a negative DIF test does not preclude a diagnosis of MMP. If trachoma is suspected in the presence of trichiasis, nucleic acid amplification tests (NAATs) on conjunctival scrapes are performed, although trachoma is usually diagnosed with clinical examination.

Most eyelash conditions are managed locally, as discussed above. In the presence of mucous membrane pemphigoid disease, the patient needs to be assessed for the involvement of other mucosal areas, such as the nasopharynx (which can cause airway obstruction), oral, genital, anal, and esophagus. If a malignancy is diagnosed as causing trichiasis/lash loss, appropriate biopsy and local and systemic management are instituted. With active trachoma, oral azithromycin and topical tetracycline are instituted. Trichiasis and/or entropion are treated appropriately with surgery (lash destruction or eyelid margin tarsal rotation surgery).

If the patient has trichiasis with conjunctival scarring and the direct immunofluorescence (DIF) is negative, a clinical examination should be performed to exclude the following diseases: Chemical burns Trauma Stevens-Johnson syndrome Atopy Graft-versus-host disease Toxicity to medication If these diseases are excluded, the patient should still be treated as having MMP, as immunomodulatory therapy is vital for controlling this disease.

Most eyelash disorders can be diagnosed through a thorough patient history and careful clinical examination. Appropriate management can provide symptomatic relief and, when indicated, prevent vision-threatening complications. In cases of trichiasis secondary to mucous membrane pemphigoid, treatment of the misdirected lashes is necessary; however, definitive surgical correction should be deferred until adequate systemic immunomodulatory therapy has been initiated. Given the unpredictable course of this condition, close and ongoing follow-up is essential and typically requires coordination among ophthalmology, dermatology, and immunotherapy specialists. Additional specialties may be involved depending on the extent of extraocular mucosal involvement. In trachoma, timely recognition and appropriate treatment are critical, as early intervention can prevent progression to vision loss and blindness.

There are a few complications seen with the focal eyelash diseases discussed. However, with mucous membrane pemphigoid disease, secondary scarring, entropion, corneal scarring, glaucoma, and vision loss are all possible, even with appropriate immunomodulation. Failure to diagnose and manage trichiasis can cause pain, ulcers, and even loss of vision.

With a diagnosis of mucous membrane pemphigoid, it is important to involve the subspecialties that can help with the mucosal involvement, including dermatology, genitourinary, gastrointestinal, immunotherapy, and ophthalmology.

Widespread education regarding the prevention, diagnosis, and treatment of Trachoma is available through the World Health Organization. In mucous membrane pemphigoid disease, the patient needs to be made aware of the other mucosal surfaces that may be involved so that they report any symptoms that may necessitate further immunomodulation therapy.

If a patient complains of eye irritation, pay particular attention to the eyelashes, as subtle findings there can cause severe discomfort, eg, cilia incarnata internum. Trichiasis may be simple (local trauma, blepharitis) or may be the first presentation of a more serious disease, such as local eyelid malignancy, mucous membrane pemphigoid, or trachoma. Beware trichotillomania. Many unnecessary investigations can be avoided. Always consider mucous membrane pemphigoid disease when seeing older patients with trichiasis. Eyelashes causing corneal irritation/ulcers can be managed with appropriate local non-surgical and surgical methods. With trachoma, blindness is preventable. With migration and population movements, all physicians need to be aware of this condition.

With conditions such as mucous membrane pemphigoid disease and trachoma, appropriate preventative, medical, surgical, and social interventions can be beneficial. In pemphigoid disease, multiple specialties need to be involved, with 1 designated "conductor" to ensure the patient's health and the course of the disease are properly managed. With trachoma, social workers, preventative health workers, and ancillary staff, including nurses, where no ophthalmologists are available, together with a careful review of the World Health Organization guidelines, is important.