Distichiasis has been observed in 94% individuals if present at birth and 75% of those present with ocular findings such as irritation of cornea, intermittent conjunctivitis, photophobia and ptosis. As described earlier, it is easy to identify and differentiate the two varieties of distichiasis based on physical appearance of aberrant eyelashes, previous history and presence or absence of underlying ocular illnesses. Typically, a slit lamp is used to examine the eye and corneal epithelium. The lamp is instilled with fluorescein dye to observe and evaluate ocular defects and abnormalities.

In acquired distichiasis, the lower eyelids are typically affected but the form and appearance of the accessory eyelashes can vary widely in different cases, from being full and heavy to very fine and light, highly pigmented and dark to very lightly pigmented or nonpigmented and adequately aligned and oriented to irregular alignment and misdirected growth. The acquired form, as mentioned before, develops as a results of chronic ocular inflammatory conditions. 

In lymphodemea-distichiasis syndrome (LD), the ocular condition persists since childhood although lymphedema develops in later years or after puberty. Therefore, children suffering from distichiasis must be evaluated for possibility of development of lyphedema and a complete family history must be taken.

• Lymphedema

  Mutations in the FOXC2 gene are associated with lymphedema-distichiasis syndrome. An important feature of lymphedema-distichiasis syndrome is that distichiasis is typically present prior to the onset of lymphedema. [ncbi.nlm.nih.gov]

  Most lymphedema is secondary—it was caused by trauma (such as cancer treatments and the like), or a disease/other condition. Primary lymphedema, lymphedema that occurs on its own is rarer. And lymphedema-distichiasis is rarer. [lymphiestrong.com]

• Inflammation

  There’s a higher change you’ll get acquired distichiasis if you: Are older, since some conditions that lead to this form of double eyelashes happen with age Are a woman, since OCP is twice as likely in women Have eyelid inflammation Wear contacts, since [webmd.com]

  Distichiasis can also be an acquired disease caused by chronic irritation or inflammation of the eye margin. Examples of such irritation and inflammation are blepharitis, meibomian gland dysfunction, meibomianitis and chemical injuries. [hypertrichosis.com]

  Causes of acquired distichiasis Many factors may cause acquired distichiasis, including: Blepharitis: This is a form of eyelid inflammation that may be chronic (long term). [my.clevelandclinic.org]

  Postoperative care of inflammation from the surgery is usually necessary and should be planned for. There are usually two or three follow-up visits to check for regrowth of the eyelashes and removal of any that return or persist. [adbadog.com]

• Asymptomatic

  A 3-year-old child, his mother, and his uncle were found to have asymptomatic distichiasis accompanied by corneal hypoaesthesia. [ncbi.nlm.nih.gov]

  His younger brother also had bilateral distichiasis of both the upper and lower eyelids, but was asymptomatic. His mother had bilateral upper eyelid distichiasis only and was also asymptomatic. [ijps.org]

  (especially in infancy and childhood) Patients may notice irritation or foreign body sensation Blurred vision TREATMENT Observation may be appropriate for infants or young, asymptomatic children If symptomatic, options for treatment include: Epilation [eyerounds.org]

  Often this condition is asymptomatic, however, when the hairs come into contact with the cornea or conjunctiva mild blepharospasm, conjunctivitis and occasionally corneal ulceration may occur. [vet-vision.com]

  Signs : asymptomatic if only fine cilia-like hairs; thicker hairs cause corneal irritation → superficial keratitis Keratitis or corneal ulceration Ulcerative keratitis. Diagnosis : signs. [vetstream.com]

• Falling

  Recently papers have been published on the association of lymphostasis with congenital distichiasis (Falls and Kertesz, 1964; Robinow et al., 1970; Jester, 1977). [ncbi.nlm.nih.gov]

  Ann Arbor 11, 69–70 (1945) Google Scholar Falls, H. F., Kertesz, E. D.: A new syndrome combining pterygium colli with developmental anomalies of the eyelids and lymphatics of the lower extremities. Trans. Am. Ophthal. [link.springer.com]

  Surgical procedures vary depending on the extension of malpositions and fall into two categories: ‘destruction’ and/or ‘repositioning’ of eyelashes/hair follicles. DEFINITION. [oculoplastica.it]

• Dysostosis

  The congenital form can be inherited with an autosomal dominant mechanism, but it can also be associated with ptosis, strabismus, congenital heart defects, mandibulofacial dysostosis or congenital lymphoedema (4). [oculoplastica.it]

  It can be isolated or associated with ptosis, strabismus, congenital heart defect, or mandibulofacial dysostosis. [emedicine.medscape.com]

  It can be isolated or associated with ptosis, strabismus, congenital heart defect or mandibulofacial dysostosis. [reviewofophthalmology.com]

• Heart Disease

  Numerous clinical associations have been reported with this condition, including congenital heart disease, ptosis, varicose veins, cleft palate, and spinal extradural cysts. [ncbi.nlm.nih.gov]

  Associated abnormalities include con- genital heart disease, spinal extradural cysts, ver- tebral abnormalities, ptosis, cleft palate and hemangiomas. [scopemed.org]

  Other features : may include varicose veins, ptosis, cleft palate and congenital heart disease References & Further reading Kaestner KH, et al. [genetics4medics.com]

• Ulcer

  If thicker hairs → corneal irritation → superficial keratitis Keratitis → corneal ulceration Ulcerative keratitis. Timecourse Juvenile. [vetstream.com]

  The folded edge of the upper tarsus, or the inturned lashes, may traumatize the cornea causing ulceration. We describe a case of unilateral upper eyelid horizontal tarsal kink associated with distichiasis and congenital corneal ulceration. [ncbi.nlm.nih.gov]

  The location of the ulcer and the distichia help us decide whether the distichia are the underlying cause of the ulcer. Temporary relief may be provided by pulling out the abnormal hair in the exam room, but these lashes almost always grow back. [animaleye.com.au]

  Sometimes distichiasis can cause corneal ulcers or erosions where the hairs touch the surface of the eye. Clinical signs of corneal ulcers are similar to those of distichiasis. [acvo.org]

  Often this condition is asymptomatic, however, when the hairs come into contact with the cornea or conjunctiva mild blepharospasm, conjunctivitis and occasionally corneal ulceration may occur. [vet-vision.com]

• Blepharitis

  He was recently treated for "blepharitis" and allergic conjunctivitis. Despite using olopatadine (Patanol) drops and lid hygiene, his symptoms persistented. [eyerounds.org]

  Examples of such irritation and inflammation are blepharitis, meibomian gland dysfunction, meibomianitis and chemical injuries. Cosmetic treatment for focal areas can be tried with epilation or epilation with electrolysis. [hypertrichosis.com]

  Acquired distichiasis may be delayed by proper treatment of diseases such as blepharitis, and ocular cicatricial pemphigoid. [nhp.gov.in]

• Strabismus

  Pediatric Ophthalmology and Strabismus Second Edition. Springer Science+ Business Media New York 2003. Roy Frederick Hampton, Fraunfelder Frederick W, Fraunfelder Frederick T, Tindall Renee, Jensvold Bree. [nhp.gov.in]

  Mutations in the Forkhead family gene FOXC2 located on chromosome 16q24.3 have been identified to be associated with this syndrome. [3] Epidural cysts, cardiac abnormalities, short stature, ptosis, microphthalmia, strabismus, partial ectropion of the [ijo.in]

  Pediatric Ophthalmology and Strabismus Third Edition. Oxford University Press 2012. P 590- 591. http://emedicine.medscape.com/article/1212908-overview [aimu.us]

  The congenital form can be inherited with an autosomal dominant mechanism, but it can also be associated with ptosis, strabismus, congenital heart defects, mandibulofacial dysostosis or congenital lymphoedema (4). [oculoplastica.it]

• Blurred Vision

  Other eye problems such as an irregular curvature of the cornea causing blurred vision ( astigmatism ) or scarring of the cornea may also occur. [rarediseases.info.nih.gov]

  Other eye problems such as an irregular curvature of the cornea causing blurred vision (astigmatism) or scarring of the cornea may also occur. [diseaseinfosearch.org]

  Related eye problems can include an irregular curvature of the cornea causing blurred vision ( astigmatism ) or scarring of the cornea. [ghr.nlm.nih.gov]

  vision TREATMENT Observation may be appropriate for infants or young, asymptomatic children If symptomatic, options for treatment include: Epilation Cryotherapy Trephination Wedge resection Microhyfrecation Lid splitting procedure with cryotherapy [eyerounds.org]

  Tearing, blurred vision, and light sensitivity often result. Diagnosis: The swelling of the arms and legs is due to inadequate drainage of the lymph and can be diagnosed by a physician. [medigoo.com]

• Corneal Opacity

  The association between epilation and corneal opacity among eyes with trachomatous trichiasis. Br J Ophthalmol. 2006;90:171-4. Collin RJO. Entropion and trichiasis. In: A Manual of Systemic Eyelid Surgery. New York: Churchill-Livingstone;1989: 7-26. [oculoplastica.it]

  opacity There is severe conjunctival inflammation and scarring accompanied by secondary keratopathy due to the close apposition between the inflamed conjunctiva and the corneal epithelium. [reviewofophthalmology.com]

• Blepharoptosis

  Both I-1 and II-1 had blepharoptosis, and II-2 had epicanthus. (C) Details of eyes with distichiasis. Note the double row of eyelashes originating from the inner margin of the eyelids, as indicated by the black arrows (II-2). [ijbs.com]

• Fracture

  Several different surgical treatment options have been previously alluded to in the literature including lamellar tarsoplasty, full-thickness eyelid fracture, and rotation and excision of the kink with tarsal reapposition. [ncbi.nlm.nih.gov]

  […] vernal keratoconjunctivitis), infectious reasons (trachoma: Picture 2; herpes zoster; parasitosis: dermodex folliculorum), autoimmune causes (ocular pemphigoid scar), or iatrogenic causes (resulting from surgeries: lower blepharoplasty, correction of fracture [oculoplastica.it]

  Surgical techniques include eyelid wedge resection, horizontal blepharotomy, tarsal fracturing and eyelid splitting. 15 Surgical or radiosurgical splitting of the lid margin allows for direct access to the lash follicles, which can then be efficiently [reviewofophthalmology.com]

It is imperative to gather a complete family history on identifying any case of distichiasis. To rule out the presence of lymphedema-distichiasis syndrome, patient's history should include asking about any signs of lymphedema that may have appeared and the patient should be counseled about possibility of development of lymphedema in lower limbs. In cases when children are diagnosed with distichiasis during early childhood, the child's parents must be counseled about lymphedema and associated genetic anomalies such as cleft palate and congenital heart disease that may ensue. Lymphedema is clinically diagnosed by lymphoscintigraphy. Presence of false negative results should be kept in mind when making diagnosis on confirmatory investigation. In some cases, genetic investigation up to the molecular level is required to spot mutations in FOXC2, an important transcription factor that plays a vital role in several developmental pathways. 

There is no specific treatment for all cases of distichiasis. Several treatment options are available and choice of treatment depends upon number of aberrant eyelashes (full or few), patient's age, presence of other comorbidities and patient's personal preference. 

For temporary symptomatic relief, lubrication therapy or epilation are employed. In lubrication therapy, an eye ointment is applied on the ocular surface to prevent abrasion of corneal epithelium and to reduce discomfort and irritation. The method, however, is not patient compliant as it cannot be used during working hours.

Epilation of the misdirected row of eyelashes is also employed to provide temporary relief. The misdirected eyelashes are isolated and removed completely from the root of hair shaft using forceps. It is highly important that the root of each hair follicle emerges out intact because any hair follicle removed incorrectly (broken along the hair shaft and not removed from the base) causes more irritation to the patient. The method is temporary as the aberrant eyelashes typically regrow within 2-3 weeks after epilation [2] [3].

Procedures for removing the misdirected eyelashes permanently include cryotherapy, direct surgical excision of eyelashes by wedge resection [9], electrolysis, argon laser ablation, diode laser and trephination. Maintenance of aseptic, sterile environment during performance of any of these procedures and use of antibiotics prophylactically are highly important to minimize the chances of infection. 

In cases when the aberrant eyelash cilia are fewer in number, electrolysis or argon laser ablation may be used. In electrolysis, topical anesthetics or general anesthesia may be required in aged and debiliated patients but the chances of recurrence are high and the eyelashes may regenerate even after the procedure. In argon laser ablation, the hair shaft of patient's accessory set of eyelashes is exposed to slit lamp equipped with argon laser. Typically, argon laser with a power of 1000-1500 mW and spot size of 50-100 µm are exposed for a duration of 0.1-0.2 seconds with provision of 12-30 laser shots to each eyelash. Depending on patient's condition, topical or local anesthetics may be required during this procedure. With argon laser ablation, chances of recurrence may vary from 12%-41%.

Cryotherapy is another procedure for a more permanent treatment of distichiasis with a success rate of 95%. In this method, nitrous oxide or carbon dioxide are used as cryogen and hair follicles of misdirected eye lashes are permanently destroyed by freezing them to a temperature of -20°C. Cryotherapy is more preferred to be used twice as double free-thaw application technique provides more effective treatment of the the misdirected eyelashes. 

Another effective procedure for treating distichiasis is the use of diode laser. In this method, 810nm diode laser with pulse length of 50ms and energy intensity of approximately 50 J/cm2 is used to treat abnormal eyelashes. The treatment is needed 4-5 times with 4-6 weeks apart to provide most effective results [10]. 

A much safer, faster alternative treatment with lesser chances of complications is trephination. In this technique, sisler ophthalamic microtrephine (1.0mm) is used to cut eyelash hair follices [11].

Surgical methods of treatment carry risk of post surgical complications which comprise hemorrhage, infection, wound dehiscence, eyelash regrowth, entropion or ectropion. Use of antibiotics and adequate electrocautery can reduce the chances of infection and hemorrhage respectively. 

Distichiasis is curable as many temporary and permanent treatment options are available. Since permanent treatment requires surgical interventions, certain post surgical complications might ensue after the procedure such as hemorrhage, infection and lid margin deformities. 

Distichiasis can be acquired or congenital. The two different forms of the disease possess different etiologies. Acquired distichiasis occurs due to metaplasia of meibomian glands into pilosebaceous glands which results in the formation of an accessory row of eye lashes. The aberrancy can develop due to chronic inflammatory conditions of eyes such as blepharitis or conjunctivitis, eye injuries or Stevens-Johnson syndrome.

The congenital form results from aberrant differentiation of meibomian glands into hair follicles during development. Congential distichiasis is autosomal dominant with complete penetration [2] [3]. 

Distichiasis develops rarely and has been reported in individuals belonging to all ethnic classes, in all age groups and equally in both male and female gender. 

The two forms of distichiasis are easily identified and differentiated. As described earlier, congenital distichiasis is a developmental condition. The disease is not presented clinically before 5 years of age as the accessory eyelashes are fine during infancy and do not cause ocular irritation. In acquired distichiasis, on the other hand, which results from a chronic inflammatory condition of the eyes, the accessory eyelashes are fine and nonpigmented and cause consistent ocular irritation. 

It is highly important to differentiate distichiasis from other apparently similar ocular illnesses. Eyelids must be examined physically for appropriate evaluation to make the correct diagnosis. The ocular conditions that must be ruled out to prevent misdiagnosis of distichiasis are trichiasis, in which the eyelashes are formed in the anteror lamella, entropion, epiblepharon which frequently occurs in children, lid scar, blepharoconjuctivitis and cicaticial conjunctivitis.

Congenital distichiasis cannot be prevented nor can be acquired distichiasis. However, it is possible to reduce the extent of edema in ymphedema-distichiasis (LD) syndrome by application of hosiery prior to the development of lymphedema. Secondary complications can be prevented by prompt treatment of any infection with antibiotics.

Distichiasis refers to a condition of eyelids that arises when primary epithelial germ cells, instead of differentiating into meibomian glands, aberrantly differentiate into pilosebaceous glands on the posterior portion of lid margin which results in the formation of an extra, abnormal row of eye lashes. The accessory eye lashes formed can either be fine and slightly pigmented or coarse and equally pigmented as normal eyelashes. This second inner row of eyelashes, because of being in close proximity to cornea, can cause corneal irritation which can lead to corneal scarring, epiphora, astigmatism and keratoconus [1]. Other ocular conditions that have been reported to be associated with distichiasis comprise corneal hypoesthesia [5], photophobia, ptosis, congenital cataracts, congenital ectropion, congenital entropion, extropia [4], absent lacrimal duct [6], epicanthus, telecanthus, eyelid edema, color blindness [7], microphthalmos, dystrophic retinal pigmentation and optic disc pallor as in the oculo-cerebro-renal syndrome [8].

Distichiasis is either identified as acquired or as congenital. Acquired distichiasis has been found to occur in certain chronic inflammatory conditions, following chemical injuries of eyelids, and in conditions like Stevens-Johnson syndrome and ocular pemphigoid. Acquired distichiasis has usually been observed in the lower eyelids but the accessory lashes formed can be full or fine, pigmented or nonpigmented, aligned or misaligned. Congenital distichiasis results from abnormal development of an accessory row of eyelashes before birth with complete penetration. The defect results from failure of the basal epithelial cells to differentiate into meibomian glands during development. Congenital distichiasis may sometimes accompany ptosis, madibulofacial dystosis, or stabismus. 

Distichiasis is also associated to be present in an autosomal dominant disorder, lymphodema-distichiasis (LD) syndrome, which is characterized by presence of lymphedema of lower limbs and formation of aberrant eyelashes on the posterior margin of eyelids [1] [4]. 

Normal eyelids contain single rows of eyelashes. The inner, posterior portion of eyelids that is close to the eyeball contains glands which produce an oily substance that becomes part of tear film. In some conditions, these glands are replaced by another accessory row of eyelashes. This condition is referred to distichiasis. The accessory eyelashes can be formed on any of the four or all four eyelids and can be fine and slightly pigmented or full and darkly pigmented. Formation of accessory eyelashes on the posterior portion of eyelid causes irritation of eyeball and in the long term, damage to its structure. 

There are two types of distichiais that are identified, congenital distichiasis and acquired distichiasis. Congenital distichiasis is typically present since childhood and is mostly found to be associated with lymphedema-distichiasis (LD) syndrome. In LD syndrome, accessory rows of eyelashes are present along with lymphedema, which is swelling of lower limbs. Acquired form of the disease is usually developed later in life, often as a result of eye injuries or inflammation. 

Distichiasis is characterized by the presence of irritation of eyeballs and visible presence of accessory set of eyelashes. It is easily identified and in case of children, a complete family history is needed to detect chances of development of LD syndrome. Parents should be counseled about regular follow ups and preventive measures that should be taken in order to avoid problems that appear later with development of lymphedema.

Several treatment options are available to treat distichiasis. Eye ointments can be used to soothe irritation by lubricating the eyeball. Epilation of accessory eyelashes by removing each lash from the hair shaft using forceps provides temporary ease and comfort but the eyelashes regenerate within 4 weeks. 

Permanent methods for treating the disease are electrolysis, cryotherapy, trephination and laser. The choice of treatment depends on number of accessory eyelashes (fewer or more) and patient's health condition. Cryotherapy is one the most effective and permanent surgical options available with a success rate of 95%. 

1. Jeffrey S. How double eyelashes give you swollen legs. Br J Ophthalmol 2002;86:1074.
2. Allen RC. Genetic diseases affecting the eyelids: what should a clinician know?. Curr Opin Ophthalmol. 2013;24(5):463-477. 
3. Butler MG, Dagenais SL, Garcia-Perez JL, et al. Microcephaly, intellectual impairment, bilateral vesicoureteral reflux, distichiasis, and glomuvenous malformations associated with a 16q24.3 contiguous gene deletion and a Glomulin mutation. Am J Med Genet A. 2012;158(4):839-849.
4. Erickson RP, Dagenais SL, Caulder MS, et al. Clinical heterogeneity in lymphoedema-distichiasis with FOXC2 truncating mutations. J Med Genet. 2001;38(11):761-766. 
5. Kremer I, Weiberger D, Cohen S, Ben Sira I. Corneal hypoesthesia in asymptomatic familial distichiasis. Br J Ophthalmol 1986;70(2):132-134. 
6. Holder-Espinasse M, de Bluis MC, Faivrel L, et al. Absent lacrimal ducts, distichiasis, dysmorphic features and brachydactyly: a case report. Clin Dysmorphol 2001;10(4):253-255. 
7. O'Donnell BA, Collin JR. Distichiasis: Management with cryotherapy to the posterior lamella. Br J Ophthalmol 1993;77(5):289-292. 
8. Brancato R, Matteini M, Cotrozzi G. Sindrome oculo-cerebro-renale in soggott portare di blefarophimosi e di distichiasis. Ann Ottal 1965;91:35-37.
9. Moosavi AH, Mollan SP, Berry-Brincat A, et al. Simple surgery for severe trichiasis. Ophthal Plast Reconstr Surg. 2007;23(4):296-297.
10. Pham RT, Biesman BS, Silkiss RZ. Treatment of trichiasis using an 810-nm diode laser: an efficacy study. Ophthal Plast Reconstr Surg. 2006;22(6):445-447.
11. McCracken MS, Kikkawa DO, Vasani SN. Treatment of trichiasis and distichiasis by eyelash trephination. Ophthal Plast Reconstr Surg. 2006;22(5):349-351.