Eyelids and Lacrimal System
Peter A. D. Rubin
I. Eyelids
The eyelids protect the eye by preventing contact with foreign materials and by preventing excessive drying of the cornea and conjunctiva. The palpebral fissure must be wide enough to allow light to enter the pupil and should close sufficiently to provide protection and moisture to the globe. The lid contours and palpebral fissures should be symmetric to avoid cosmetic deformity.
Eyelid anatomy. The eyelids are lamellar structures covered on their outer surfaces by skin and on their inner surfaces by conjunctiva. Between the skin and conjunctiva are the fibrous tarsal plates, the orbital septum, the upper lid elevators (levator muscle, levator aponeurosis, and Müller muscle), and the lower lid retractors (inferior rectus fascia and inferior tarsal muscle). The levator muscle is innervated by the third cranial nerve, whereas the Müller and inferior tarsal muscles are innervated by sympathetic nerves. The lids and palpebral fissures are maintained in a stable position by periosteal attachments provided by the medial and lateral canthal tendons. The palpebral fissure is closed by the orbicularis muscle, which is innervated by the seventh cranial nerve.
Congenital and developmental eyelid anomalies
Ptosis. Most congenital ptosis is caused by a deficiency of the striated fibers in the levator muscle. Many cases of congenital ptosis are associated with other developmental abnormalities, such as blepharophimosis and epicanthus. Congenital ptosis will be discussed with other eyelid malpositions (see Section I.C.1).
Blepharophimosis and epicanthus. Blepharophimosis is a generalized narrowing of the palpebral fissure. This abnormality is frequently associated with congenital ptosis and epicanthus. Epicanthus is a semilunar fold of skin that crosses the medial canthus. Blepharophimosis and epicanthus should usually be repaired prior to surgical correction of ptosis.
Colobomas are usually full-thickness defects in the medial portions of the upper lids. They are often associated with other congenital defects, such as facial dermoids. Unless exposure keratopathy occurs, surgical repair of most colobomas can be delayed until the child is several years old.
Ankyloblepharon is an abnormal fusion of the upper and lower eyelid margins, usually near the lateral canthus. The fused lids may be surgically divided if the attachment is cosmetically disfiguring.
Ectropion and entropion are both uncommon congenital disorders (see Sections D and E). Congenital ectropion is usually minimal and may be associated with blepharophimosis. Congenital entropion is quite unusual but is frequently confused with epiblepharon.
Epiblepharon is a relatively common condition in which a prominent skin fold is present in front of the tarsus, usually near the medial margin of the lower lid. The lashes may be rotated inward without actual rotation of the eyelid margin (entropion). Surgical correction is seldom required because epiblepharon usually resolves spontaneously.
Ptosis is a malposition of the upper eyelid in which the lid margin is abnormally low because of insufficient upper eyelid retraction. Evaluation of a patient with ptosis should include measurement of palpebral fissure heights, distance from the pupillary light reflex to the upper eyelid margin (marginal reflex distance and levator function, excursion of the upper eyelid margin from downgaze to upgaze, while fixating the brow in a stable position). Complete ptosis evaluation should also include assessment
of the protective mechanisms of the globe, including Bell phenomenon, corneal sensation, and baseline tear production (Schirmer test). The positions of the eyelid folds and any abnormalities of the extraocular muscles should be documented. The type of ptosis should be carefully established by history because treatment of congenital ptosis is usually different from that for acquired ptosis. Both congenital and acquired ptosis must be distinguished from pseudoptosis, a condition in which the upper eyelid appears to be low but lid elevation is adequate. Pseudoptosis of the lid margin may be due to descent of the brows (brow ptosis) or excessive skin and fat of the upper eyelid mechanically lowering the upper eyelid margin (dermatochalasis).
Congenital ptosis is usually unilateral, although approximately one-fourth of the cases involve both upper eyelids. It may be associated with other abnormalities:
Blepharophimosis–epicanthus inversus-ptosis syndrome.
Marcus Gunn “jaw-winking” syndrome, a synkinesis in which the ptotic eyelid is elevated with movement of the mandible.
Extraocular muscle palsies, particularly those involving the superior rectus and inferior oblique muscles ipsilateral to the ptosis.
Treatment of congenital ptosis usually requires resection of part of the weak levator muscle and aponeurosis, or suspension of the lids from the frontalis muscle (brow).
Acquired ptosis is frequently associated with good levator muscle function and may be categorized according to etiology.
Involutional ptosis is the most common ptosis encountered, often involves both upper lids of older patients, and may occur following cataract extraction. This is the most common form of acquired ptosis and is caused by stretching of the levator aponeurosis or disinsertion of the levator muscle from its insertion onto the tarsus.
Myogenic ptosis may be associated with a variety of muscular disorders, including myasthenia gravis, oculopharyngeal muscular dystrophy, and progressive external ophthalmoplegia.
Neurogenic ptosis can be caused by deficient innervation of the third cranial nerve to the levator muscle or deficient sympathetic innervation to the Müller muscle.
Traumatic ptosis may result from lacerations of the levator muscle or aponeurosis and may sometimes follow severe blunt trauma with eyelid edema.
Mechanical ptosis may be associated with lid tumors such as neurofibromas and may result from scars or foreign bodies.
Treatment of acquired ptosis involves correcting the cause of the ptosis, typically repair of the levator aponeurosis (tendon), if possible. If levator function is not good, this involves a larger resection of the levator aponeurosis, including the distal levator muscle; in more severe cases, the levator aponeurosis may be suspended from the Whitnall ligament—the suspensory ligament of the levator muscle located just posterior to the orbital rim. In cases where the levator function is especially poor, <5 mm, the eyelid may be coupled to the brow via frontalis muscle suspension using a either autologous, homograft, or synthetic materials.
Pseudoptosis is a condition in which the upper eyelid appears to be abnormally low without insufficiency of the lid retractors. Causes of pseudoptosis include:
Epicanthus and facial asymmetry.
Excessive upper eyelid skin, as found in dermatochalasis (very common).
Contralateral palpebral fissure widening.
Palpebral fissure narrowing associated with adduction in Duane retraction syndrome.
Hypertropia or contralateral hypotropia.
Enophthalmos or contralateral exophthalmos.
Ectropion is a malposition of the eyelid in which the lid margin is rotated away from the globe. The lower lid is involved much more commonly than the upper lid.
Ectropion sometimes leads to exposure keratopathy and conjunctival hypertrophy. Tearing may result from eversion of the lacrimal punctum if the ectropion involves the medial lid.
Congenital ectropion is quite uncommon, although it may be found with blepharophimosis. Treatment is rarely required because the eversion is usually minimal.
Acquired ectropion is categorized on the basis of etiology.
Involutional ectropion is relatively common and is a frequent cause of tearing (epiphora). This abnormality is caused by attenuation of the lower eyelid retractors, the orbicularis muscle, and the canthal tendons. Treatment involves horizontal eyelid shortening and canthal suspension. If punctal eversion is the most significant feature, conjunctival shortening and a punctoplasty may reduce tearing.
Paralytic ectropion usually results from seventh nerve injury, with resulting drooping of the lower lid and widening of the palpebral fissure. Treatment may require tarsorrhaphy, horizontal lid shortening, canthoplasty, or suspension of the upper cheek. A flaccid brow and upper lid may be surgically elevated if they partially cover the palpebral fissure.
Mechanical ectropion may be caused by abnormalities that push or pull the lid away from the eye. Treatment usually involves treatment of the underlying abnormality.
Cicatricial ectropion occurs when the anterior lamella of the eyelid (skin and orbicularis muscle) is contracted by a variety of possible causes (e.g., burns, tissue loss, traumatic scars, or inflammation). Linear and circumscribed scars may respond to massage or relaxing operations. More extensive cicatricial ectropion usually requires a skin graft.
Entropion is a malposition of the eyelid in which the lid margin is rotated toward the globe. Entropion is functionally important because inturned lid margins may damage the cornea and produce keratitis or ulceration. Related conditions that should be differentiated from entropion are epiblepharon, trichiasis, and distichiasis.
Congenital entropion is very rare and usually associated with other abnormalities, such as tarsal hypoplasia or microphthalmia. Congenital entropion may be confused with epiblepharon, a mild deformity that usually resolves spontaneously. Depending on severity, this condition may be treated similarly to acquired entropion.
Acquired entropion is a common disorder that is usually either involutional or as a result of aging or cicatricial changes, resulting from tarsoconjunctival shrinkage.
Involutional entropion usually involves the lower lid and is caused by degenerative changes similar to those that cause involutional ectropion. With aging, atrophy of the orbital tissues can lead to a relative enophthalmos and a tendency for inward rotation of already attenuated eyelid structures. Treatment should be directed toward correction of those abnormalities that are most prominent. Penetrating pretarsal cautery or three Quickert lid eversion sutures may temporarily correct a moderate entropion, but may be followed by recurrence. Many operations have been devised for correction of involutional entropion. The most physiologic procedures are those that restore the action of attenuated eyelid retractors and tighten a lax lower lid and the insertion of the lateral canthal tendon.
Spastic entropion is a temporary or intermittent accentuation of involutional changes caused by irritation and vigorous lid closure. Treatment can be directed toward removing the cause of irritation or treating the underlying involutional abnormalities. Typically, a suture repair (Quickert) is curative of a purely spastic entropion.
Cicatricial entropion is usually the result of tarsoconjunctival shrinkage. This may be caused by a wide variety of disorders, including trachoma, Stevens-Johnson syndrome, pemphigus, ocular pemphigoid, and mechanical, thermal, or chemical injury. Cicatricial changes are often accompanied by trichiasis,
reduced tear production, mucosal keratinization, and punctal occlusion. Treatment may consist of marginal rotation of the lid margin and grafts of mucosa or other tissue to replace contracted tarsus and conjunctiva.
Blepharospasm is a disorder of unknown cause that involves involuntary closure of the eyelids. The severity of this closure ranges from mild increased frequency of blinking to severe spasms that completely occlude the eyes. Essential blepharospasm, in which the eyelids are chiefly involved, is distinguished from conditions such as Meige disease, in which lower face and neck muscles also spasm, and hemifacial spasm, which may be caused by facial nerve compression. Excision of facial muscles (myectomy) and nerves (neurectomy) has been used in the past as treatment for severe cases of essential blepharospasm. Currently, botulinum toxin injections
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