Symblepharon - Types, Causes, Pathophysiology and Treatment

What Is Symblepharon?

Symblepharon is a rare pathologic condition of the external eye that occurs due to various external factors. Symblepharon refers to a partial or complete pathological adhesion of the palpebral conjunctiva to the bulbar conjunctiva and may also involve both eyes. The adhesion may or may not involve the cornea. The adhesion is formed by a fibrous tract connecting both conjunctivae.

What Is the Anatomy of the External Eye and the Eyelid?

The eye sits in a protective bony socket called the orbit to which the six extraocular muscles attach that aid in up-down, sideways, and rotation of the eyeball. The white part is the sclera, the pigmented region is the iris that acts like a shutter, and the central part is the cornea that helps in focusing. The eye is covered externally by a thin membrane called the ocular or the bulbar conjunctiva.

The eyelid is divided anatomically into anterior, middle, and posterior lamella. Horizontally across, the upper eyelid consists of five layers: skin and subcutaneous tissue, orbicularis oculi, tarsal plates, levator apparatus, and conjunctiva. The conjunctiva, known as the palpebral conjunctiva, is a part of the posterior lamella.

What Are the Types of Symblepharon?

Based on the degree and severity of conjunctival fusion, symblepharon is of three types:

1. Anterior: Adhesion is present only on the anterior part (tip of the eyelid).

2. Posterior: Adhesion present in the fornices (junction of bulbar and palpebral conjunctiva).

3. Total: Adhesion of the entire eyelid.

What Causes Symblepharon?

Symblepharon is caused due to healing of the kissing raw surfaces after any infection or injury.

The etiology includes:

• Atopic keratoconjunctivitis (due to overproduction of antibodies against an allergen).

• Atopic conjunctivitis (acute, intermittent, or chronic conjunctival inflammation from air-borne allergens).

• Toxic epidermal necrosis (drug-induced exfoliation of the epidermis and mucous membranes over 30% of the body surface and with a potential fatality).

• Stevens-Johnson syndrome (reaction to medication present over 10% of the body surface).

• Erythema multiforme (an allergic reaction affecting the skin).

• Ocular cicatricial pemphigoid (autoimmune conjunctivitis).

• Pseudopemphigoid conditions.

• Trauma to the eye that breaks the continuity of the conjunctiva.

• Conjunctival burns of chemical (like alkali burns) or thermal origin.

• Porphyria cutanea tarda (photosensitive reaction on the skin).

• Rosacea (flushing of facial blood vessels).

• Epidemic keratoconjunctivitis (contagious conjunctivitis from adenovirus).

• Xeroderma pigmentosum (hereditary, and extreme sensitivity to ultraviolet radiation).

• Squamous papilloma of the conjunctiva (benign tumor with the outgrowth of epithelial and stromal elements of the conjunctiva).

• Venereal conjunctivitis (conjunctivitis with a sexually transmitted origin).

• Chlamydial conjunctivitis (conjunctivitis from Chlamydia).

• Bacterial conjunctivitis (conjunctivitis with a bacterial origin).

• Conjunctival hyperemia (blood flow to the conjunctiva increases due to vasodilation).

• Sarcoidosis (tiny collections of inflammatory cells in different parts of the body).

What Is the Pathophysiology of Symblepharon?

Due to various etiologies, the bulbar or palpebral conjunctiva, or both undergo trauma and lose their continuity. The fusion of conjunctivas occurs due to abnormal healing post-injury. Whatever the inciting injury, the loss of epithelial cells from both conjunctivas led to their adhesion.

What Are the Signs and Symptoms of Symblepharon?

• Ocular motility disorders.

• Diplopia (double vision).

• Lagophthalmos (inadequate lid closure).

• Obliterated fornix.

• Entropion (inward folding of the eyelid).

• Corneal exposure.

• Increased blinking.

• Keratinization of the ocular surface.

• Decreased extraocular movement.

• Tearing.

• Redness.

• Burning.

• Foreign body sensation.

• Photophobia.

• Lid heaviness.

• Blepharospasm (abnormal contraction of the eyelid muscles).

How to Treat Symblepharon?

Prophylactic Treatment

Initial therapy involves:

• Copious irrigation.

• Checking and managing pH levels.

• Debridement of any necrotic conjunctiva or particulate matter.

• Frequent irrigation.

• Topical antibiotics.

• Cycloplegic drugs.

• Therapeutic oversized contact lens.

Pharmacotherapy:

• Rituximab.

• Azathioprine.

• Cyclophosphamide.

• Mycophenolate.

In the initial raw stage, symblepharon lysis can be done multiple times a day using a glass rod which involves coating a glass rod with a lubricant and sweeping around the fornices. This can break any kind of adhesion in the initial stages.

Surgical Treatment:

Corrective procedures take into account corneal involvement, its damage, and its severity. Oculoplastics or oculoplastic surgery can be performed as a corrective measure that consists of various procedures that deal with the orbit, eyelid, tear duct, and face. It also deals with the reconstruction of the eye and associated structures damaged from symblepharon or its etiology.

Symblepharectomy procedure involves removal of the adhesion followed by reconstruction of the conjunctiva. The steps of the surgery follow symblepharon lysis with buccal mucosal grafts, conjunctival autografts, or amniotic membrane transplantation.

The surgical options are:

• Plain surgical excision.

• Surgical excision with free conjunctival limbal autograft.

• Surgical excision with amniotic membrane and myosin-C.

• Surgical excision with lamellar keratotomy and lamellar keratoplasty.

Buccal mucosal grafts can be easily harvested without significant scarring from the mucous membrane from the lip, which contains goblet cells that may stabilize the tear film by secreting mucin. Conjunctival autograft involves resecting conjunctiva and transplanting it to the raw excised area. Amniotic membrane transplantation supports re-epithelialization by promoting migration, adhesion, and differentiation of epithelial cells, and suppresses the immune and inflammatory response. During stem cell transplantation, the transplant should be avoided during active inflammation.

What Is the Prognosis of Symblepharon?

Symblepharon has a variable prognosis based on its severity and involvement in critical regions. In some cases, the condition may be asymptomatic and non-progressive, hence completely devoid of any corneal involvement giving a good prognosis. In other cases, which have severe adhesions and involve a wider region, it may cause permanent vision loss with significant scarring even after surgical excision.

What Are the Complications of Symblepharon?

• Permanent vision loss.

• Permanent diplopia.

• Ocular motility dysfunction.

Conclusion

Symblepharon is a preventable condition. With proper eye protection, while handling chemicals, and heat-protective eyewear in a high-temperature environment, timely management of underlying conditions can prevent the occurrence of any adhesion of conjunctivas. In the case of initial adhesions, suitable prophylactic measures can be undertaken to reduce the severity and prevent any complications. Post-surgical care is essential, as adhesion is prone to recurrence even with the inclusion of autografts.