Blatt Distichiasis

Clinical Characteristics
Ocular Features: 

Distichiasis, or two rows of eyelashes, is sometimes confused with districhiasis (three rows of lashes) or trichiasis.  True distichiasis often occurs in all four lids and is sometimes associated with other lid anomalies such as ptosis, trichiasis, corneal damage, congenital ectropion and absence of Meibomian glands.  It has occasionally been found only in the lower lids and much more rarely just in the upper lids. In distichiasis, the second row of lashes emerges from the orifices of the Meibomian glands which distinguishes it from acquired trichiasis in which the normally placed lashes are misdirected.  The abnormal lashes are usually thinner, shorter, and less pigmented than the normal lashes.  They number from 3-20 with an average of 12-15.

Systemic Features: 

No consistent systemic associations have been reported.

Genetics

Pedigrees consistent with autosomal dominant inheritance have been reported but no locus or gene has been identified. 

A Chinese family with affected father and one affected male and female offspring has been reported with distichiasis but no lymphedema.  A premature stop codon was found in the FOXC2 transcription gene (16q24.1) in these family members suggesting that they may have had the lymphedema-distichiasis syndrome (153400) instead. 

In some patients with anhidrotic ectodermal dysplasia (224900) there is also a double row of lashes but these exit anterior to the Meibomian gland orifices.

Distichiasis also occurs as part of the lymphedema-distichiasis syndrome (153400) as well as the blepharocheilodontic syndrome (119580). Aberrant rows of eyelashes have been reported in Setleis syndrome (227260).

Treatment
Treatment Options: 

Electrolysis of misdirected lashes may be used when individual lashes cause corneal damage.

References
Article Title: 

Distichiasis

Fox SA. Distichiasis. Am J Ophthalmol. 1962 Jan;53:14-8.

PubMed ID: 
13894397

References

Zhang L, He J, Han B, Lu L, Fan J, Zhang H, Ge S, Zhou Y, Jia R, Fan X. Novel FOXC2 Mutation in Hereditary Distichiasis Impairs DNA-Binding Activity and Transcriptional Activation. Int J Biol Sci. 2016 Aug 6;12(9):1114-20.

PubMedID: 27570485

Fox SA. Distichiasis. Am J Ophthalmol. 1962 Jan;53:14-8.

PubMedID: 13894397

Pico G. Congenital ectropion and distichiasis; etiologic and hereditary factors: a report of cases and review of the literature. Am J Ophthalmol. 1959 Mar;47(3):363-87.

PubMedID: 13627093

Blatt, N. Districhiasis congenita vera. Z. Augenheilk. 53: 325-338, 1924