# Distichia

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{{Short description|Eyelash growth from an abnormal part of the eyelid}}
{{For|the genus of plant|Distichia (plant)}}
{{Infobox medical condition (new)
| name            = Distichia
| image           = Canine distichiae.JPG
| caption         = Distichiae of the upper and lower lid of a dog
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| field           = [Ophthalmology](/source/Ophthalmology)
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A '''distichia''' is when [cilia](/source/cilia) (eyelashes) arise from the [free lid margin](/source/free_lid_margin). This abnormality, attributed to a [genetic mutation](/source/genetic_mutation), is a common [opthalmological disorder](/source/Canine_ophthalmology) of the dog. Distichiae usually exit from the duct of the [meibomian gland](/source/meibomian_gland) at the eyelid margin. They are usually multiple, and sometimes more than one arises from a duct. They can affect either the upper or lower eyelid and are usually bilateral. The lower eyelids of dogs usually have no eyelashes.<ref>{{cite web | last = Brooks | first = Dennis E. | title = Ophthalmic Examination Made Ridiculously Simple | work = Proceedings of the 30th World Congress of the World Small Animal Veterinary Association | year = 2005 | url = http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2005&PID=10923&O=Generic | access-date = 2007-02-20 }}</ref>

Distichiae usually cause no symptoms, because the lashes are soft, but they can irritate the eye and cause tearing, squinting, inflammation, [corneal ulcer](/source/Corneal_ulcers_in_animals)s and scarring.<ref>{{cite web | title = Eyelids: Conformational Abnormalities | work = The Merck Veterinary Manual | year = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/30105.htm | access-date = 2007-02-20 }}</ref> Treatment options include manual removal, [electrolysis](/source/electrology), [electrocautery](/source/cauterization), [cryotherapy](/source/cryosurgery), and [surgery](/source/surgery).
==Symptoms==
When cilia grow into the cornea it can cause irritation and damage the cornea causing [blepharospasm](/source/blepharospasm) and [lacrimation](/source/lacrimation). [Neovascularisation](/source/Neovascularisation) and [ulceration](/source/ulceration) can occur in severe cases.<ref name="eyelid"/>
==Treatment==
[Epilation](/source/Epilation) is a temporary treatment that needs to be performed roughly every 4 to 5 weeks. The procedure does not require anaesthetic and can be performed by a non-veterinarian in some cases. Permanent treatment requires the hair follicle to be removed or destroyed, with the most common technique being [cryosurgery](/source/cryosurgery). For surgery the eyelid is inverted using [Von Graefe's forceps](/source/Von_Graefe's_forceps) or a [chalazion clamp](/source/chalazion_clamp) to expose the affected follicles. For cryosurgery temperatures of −25°C are used, which destroys the follicle but not the rest of the tissue. Temperatures of −30°C or more will cause necrosis of the eyelid tissue. [Depigmentation](/source/Depigmentation) is a side effect of the procedure that typically resolves in 6 months but may be permanent. Scarring and distortion are also possible side effects of cryosurgery. [Celsus–Hotz resection](/source/Celsus%E2%80%93Hotz_resection) can be used when the entire eyelid is affected, but will cause mild [entropion](/source/entropion). Other methods of treatment include [diathermy](/source/diathermy), [electrolysis](/source/electrolysis), [partial tarsal plate excision](/source/partial_tarsal_plate_excision), and [transpalpebral conjunctival dissection](/source/transpalpebral_conjunctival_dissection)<ref name="eyelid"/>
==Epidemiology==
Some canine breeds are affected by distichiasis more frequently than others:<ref name=Gelatt_1999/>
* [Cocker Spaniel](/source/Cocker_Spaniel)
* [Dachshund](/source/Dachshund) (especially the miniature longhaired Dachshund)
* [Bulldog](/source/Bulldog)
* [Pekingese](/source/Pekingese)
* [Yorkshire Terrier](/source/Yorkshire_Terrier)
* [Flat-Coated Retriever](/source/Flat-Coated_Retriever)
* [Shetland Sheepdog](/source/Shetland_Sheepdog)
* [Boxer](/source/Boxer_(dog))
* [Poodle](/source/Poodle)<ref name=Gelatt_1999>{{cite book|editor=Gelatt, Kirk N.|title=Veterinary Ophthalmology|edition=3rd|publisher=Lippincott, Williams & Wilkins|year=1999|isbn=0-683-30076-8}}</ref>

==Ectopic cilia==
An ectopic cilia is a special type of distichia usually found in younger dogs. Commonly affected breeds include the [Flat-Coated Retriever](/source/Flat-Coated_Retriever), [Pekingese](/source/Pekingese), [Shih Tzu](/source/Shih_Tzu), [Cavalier King Charles Spaniel](/source/Cavalier_King_Charles_Spaniel), [Boxer](/source/Boxer_dog), [English Bulldog](/source/English_Bulldog), [Poodle](/source/Poodle), and [Jack Russell Terrier](/source/Jack_Russell_Terrier). The eyelash exits through the [conjunctiva](/source/conjunctiva) of the eyelid facing toward the eye, usually at the middle of the upper eyelid. It can cause intense pain and [corneal ulcer](/source/corneal_ulcer)s. Treatment is surgery or cryotherapy.<ref name="eyelid">{{cite book | last1=Gelatt | first1=Kirk N. | last2=Plummer | first2=Caryn E. | title=Essentials of Veterinary Ophthalmology | publisher=Wiley | date=2022-08-12 | isbn=978-1-119-80132-0 | doi=10.1002/9781119801368.ch6 | url=https://onlinelibrary.wiley.com/doi/book/10.1002/9781119801368|pages=239–269}}</ref>

==See also==
* [Trichiasis](/source/Trichiasis)
* [Lymphedema distichiasis](/source/Lymphedema_distichiasis)

==References==
<references/>

== External links ==
{{Medical resources
|   DiseasesDB     = 33329
|   ICD10          = {{ICD10|Q|10|3|q|10}}
|   ICD9           = {{ICD9|743.63}}
|   ICDO           =
|   OMIM           = 126300
|   MedlinePlus    =
|   eMedicineSubj  = oph
|   eMedicineTopic = 603
|   MeshID         =
}}
{{Congenital malformations and deformations of eye, ear, face and neck}}

Category:Dog diseases
Category:Congenital disorders of eyes
Category:Eyelash

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Adapted from the Wikipedia article [Distichia](https://en.wikipedia.org/wiki/Distichia) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Distichia?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.