What is Ankyloblepharon ?
Ankyloblepharon is defined as adhesion of the edges of upper eyelid with the lower eyelid. The eyelids maintain their integrity and identity. The condition is usually congenital but may be acquired. In congenital ankyloblepharon, the fused eyelids fail to separate completely during development of embryo. Congenital ankyloblepharon is caused by developmental arrest leading to aberration in growth at either medial or lateral canthus. It may occur as a sporadic finding or in association with chromosomal/syndromic conditions.
Ankyloblepharon may be complete, partial, or interrupted. In interrupted form, known as ankyloblepharon filiforme adnatum (AFA), epithelial bands are present between the lower and upper eyelids. These fine extensile cords attaching lower and upper eyelids may be single or multiple. The cords decrease the palpebral fissure height and reduce excursion of eyelids. It is reported in trisomy 18. In autosomal dominant Hay-Well’s syndrome, ankyloblepharon may be associated with ectodermal dysplasia and cleft lip/palate. In partial ankyloblepharon, the horizontal palpebral fissure is shortened.
Ankyloblepharon filiforme adnatum is a form first described by Von Hasner in the year 1881.
Ankyloblepharon may also develop following
- chemical injuries to the eyes.
- Trauma.
- Cicatrising diseases such as Stevens-Johnson syndrome or cicatricial ocular pemphigoid.
- Inflammatory diseases such as herpes simplex infection or ulcerative blepharitis.
Ankyloblepharon Symptoms
Patients may have symptoms such as
- Complete, partial, or interrupted fusion of upper and lower eyelids.
- Horizontal foreshortening of the palpebral fissure.
- Pseudoexotropia due to lateral ankyloblepharon.
- Pseudoesotropia due to medial ankyloblepharon.
- Reduced eyelid excursion.
- Associated features such as anophthalmos (absence of eyeball), microphthalmos (small eyeball), ptosis (drooping of eyelid), or cleft lip.
- Downward displacement of lateral canthal angle.
- Large fluid cyst due to accumulation of lacrimal tears in cases of total ankyloblepharon.
Ankyloblepharon Causes
Congenital ankyloblepharon:
There is epithelial fusion of the eyelid margins of the developing foetus at about 9th week of gestation. Complete separation usually does not occur until about 7th month of foetal life. Rarely, the lid margins may remain fused at birth, which results in ankyloblepharon. The exact mechanism is still not clear. The problem may be in the epithelium fusion stage, in which there is fusion of the mesoderm of the lid margin rather than purely the epithelium.
Ankyloblepharon may be an isolated sporadic malformation. It may also be associated with other malformations which are presumably inherited as an autosomal dominant condition in some cases and as an autosomal recessive condition in others.
Congenital ankyloblepharon may be associated with central nervous system and/or cardiac anomalies, cleft lip and/or palate and gastrointestinal abnormalities.
- Hay-Wells syndrome: A rare autosomal dominant disorder, known as Hay-Wells syndrome, may be associated with ankyloblepharon, ectodermal defects, and cleft lip and palate (AEC syndrome).
- Curly hair, ankyloblepharon and nail dysplasia (CHAND) syndrome: This is an autosomal recessive disorder which is characterised by ankyloblepharon and ectodermal dysplasia, but affected patients have curly hair and hypoplastic nails, with absence of cleft lip or palate.
- Edwards’ syndrome or Trisomy 18: Edwards’ syndrome or Trisomy 18 patients may also have ankyloblepharon filiforme adnatum.
- Rapp-Hodgkin syndrome: This is an autosomal dominant syndrome characterised by ectodermal dysplasia, cleft lip and/or palate, and mid-facial hypoplasia.
Acquired ankyloblepharon:
Various aetiologies for acquired ankyloblepharon have been described.
- Chemical injuries to the eyes
- Burns.
- Stevens-Johnson syndrome.
- Post traumatic prolonged contact of upper and lower eyelid.
- Trachoma.
- Ulcerative blepharitis.
- Herpes simplex blepharoconjunctivitis.
- Diphtheritic conjunctivitis.
Ankyloblepharon Diagnosis
Diagnosis of ankyloblepharon is based on clinical features.
Congenital ankyloblepharon
The eyelid margins are usually fused laterally, and less commonly medially. This condition may be associated with other developmental anomalies such as ptosis, microphthalmos, anophthalmos, or cleft lip. Lateral canthal angle may be displaced downward giving an anti-mongoloid appearance to the palpebral fissure. Lateral canthal tendon is lax or not developed so that there is significant laxity of the lower eyelids.
In ankyloblepharon filiforme adnatum, one or more narrow epithelial strands connect the central part of lower and upper eyelid margins. These vary in dimensions from 0.5 mm to 5 mm in width, and may range from 1 mm to 10 mm in length. The zone of attachment lies between the meibomian gland orifices and the eyelashes.
In total ankyloblepharon, lacrimal secretions may accumulate beneath the eyelids forming a fluid cyst.
Acquired ankyloblepharon
Commonly, acquired ankyloblepharon is due to progressive conjunctival scarring resulting in fusion of the eyelids. Patients usually have a history of progressive scarring related to the primary disease. The eyelids show fusion from scar tissue.
Investigations
Detailed ocular examination is performed including measurement of intraocular pressure. Any ocular features of hydrocephalus are noted.
Screening may be required to rule out any genetic disorder associated with ankyloblepharon.
Differential diagnosis
Ankyloblepharon may be differentiated from
- Blepharophimosis: In blepharophimosis, the palpebral aperture is reduced and there is telecanthus (increased medial intercanthus distance), but the eyelid margins are normal.
- Euryblepharon: In both euryblepharon and ankyloblepharon, the lateral portion of the eyelid may be lax and displaced downward. In ankyloblepharon, the eyelid margins are fused together for some distance producing a shorter horizontal palpebral fissure. The fissure is longer than normal in cases of euryblepharon .
- Cryptophthalmos (congenital absence of eyelid with skin passing continuously from head to cheeks over mal-formed eye).
- Microphthalmos (small eyeball).
- Pseudostrabismus.