Evaluation and management of congenital ptosis

Levator function and the amount of ptosis are used to determine which surgical approach to take.

Congenital ptosis, or dysmyogenic ptosis, is the most common ptosis seen in childhood. It comprises a group of diseases in which the ptosis is due to a developmental dystrophy of the levator muscle characterized by fibrosis and deficiency of striated muscle fibers. Most cases of congenital ptosis are idiopathic. However, congenital ptosis may occur through autosomal dominant inheritance. Common familial occurrences suggest that genetic or chromosomal defects are likely. There is no known racial or gender preference, and roughly 75% of cases are unilateral. The condition may be associated with anisometropia, astigmatism, strabismus or amblyopia. Incidence of amblyopia was measured to be 20%, of which 3% was attributable to the ptotic occlusion of the pupil.

Clinical exam

The ptosis may be mild, in which the lid partially covers the pupil. These patients present with ptosis alone without eyebrow or head positioning. However, if the ptosis is severe, the eyelid completely covers the pupil, there is poor levator function, and the brow or brows may be elevated with a chin-up position. In the past, the chin elevation positioning was considered a sign of fusion and thus indicated a low risk of amblyopia. It has recently been shown that chin elevation does not rule out the presence of significant amblyopia. Patients with congenital ptosis with poor levator function have a poorly formed eyelid crease, and they exhibit lid lag on down gaze indicative of a dystrophic muscle. A history of fluctuating ptosis with strabismus may indicate myasthenia gravis.

Causes

In most cases of congenital ptosis, the cause is idiopathic. However, congenital ptosis has been found to be associated with numerous other conditions.

Marcus-Gunn jaw-winking ptosis accounts for approximately 5% of cases of congenital ptosis. It is an example of synkinesis, or an abnormal innervation connecting two groups of normally unrelated muscles. This causes the involved eyelid to retract when the mouth opens and the mandible moves to the opposite side of the ptotic lid. This most often is a result of contraction of the external pterygoid muscle. One may also see the eyelid elevate after teeth clenching and the use of the internal pterygoid muscle.

Blepharophimosis syndrome is an autosomal dominant bilateral condition characterized by severe ptosis, epicanthus inversus, telecanthus, phimosis and ectropion.

A small percentage of patients may have an associated superior rectus weakness because the levator muscle and the superior rectus muscle arise from the same embryologic origin. Less commonly, a third cranial nerve palsy may exist. There are usually signs of aberrant regeneration present, and the pupil may be paradoxically small and nonreactive.

Horner’s syndrome is characterized by mild ptosis, miosis and anhidrosis. The ipsilateral lower eyelid may be elevated. Also, because of the lack of sympathetic innervation to the iris melanocyte development, heterochromia may exist. Periorbital tumors, such as plexiform neuroma, lymphoma, leukemia, rhabdomyosarcoma, neuroma, neurofibroma or other deep orbital tumors, may produce ptosis or proptosis.

Kearns-Sayre syndrome, a mitochondrial deletion disorder, is characterized by progressive external ophthalmoplegia, heart block, retinitis pigmentosa and central nervous system manifestations. This condition begins in childhood but is rarely present at birth. The conditions are most likely to become symptomatic in the first or second decade of life. Bilateral ptosis is a prominent feature of this syndrome. These patients should get an EKG.

Myasthenia gravis is a defect at the neuromuscular junction that produces unresponsiveness to released acetylcholine, resulting in ptosis. Ptosis tends to be variable. If this diagnosis is being considered, further testing can be done, including an ice test, a Tensilon test or a single fiber electromyography.

Evaluation of the patient

A complete ophthalmic exam with particular attention to visual acuity and possible amblyopia must be performed.

Evaluation of ocular motility is also essential. In a series of 113 patients, 31% were found to have strabismus, and of these, 3% of the cases were believed to be caused by ptosis that disrupted binocular vision.

Tear function should be evaluated if any doubt exists about the adequacy of tear production. An exophthalmometer can be used to assess relative proptosis or enophthalmos of each eye.

The pupillary size and iris color differences between the eyes should be examined for Horner’s syndrome.

The patient should be examined for Bell’s phenomenon. This evaluation can help the surgeon to determine the risk of exposure keratopathy after eyelid surgery.

External examination should also be performed with palpation of the eyelids and orbital rim. A lid mass can cause extra weight in the lid, resulting in ptosis. Plexiform neuroma, lymphoma or leukemia can result in an eyelid mass. Rhabdomyosarcoma may result with a mass that is palpable through the lid.

Because corrective surgery of children must be done under general anesthesia, it is important to get good preoperative measurements. With unilateral ptosis, the amount of ptosis is measured as the distance between the upper and lower eyelid margins with the brow in a relaxed position. In bilateral ptosis, the amount of ptosis is determined by the marginal reflex distance. This is the distance from the corneal light reflex to the upper lid margin. A normal marginal reflex distance is 4 to 4.5 mm. Levator function is measured by having the patient look down, and with a hand on the patient’s forehead to prevent any brow action, asking the patient to look upward as far as possible without a change in head position. The distance the upper lid margin elevates in millimeters is the levator muscle function. The levator muscle function is approximately 15 mm.

Treatment

Traditionally, surgery is delayed until the child is 4 to 5 years old. This allows for more patient cooperation and therefore more accurate preoperative measurements. At this age, the eyelid tissues are larger as well. However, earlier intervention may be required if the pupillary axis is completely covered, putting the patient at risk of deprivation amblyopia or if the patient acquires a significant chin-up position. Marcus Gunn jaw-winking ptosis must be ruled out because the condition is treated differently from the standard congenital ptosis. That discussion, however, is out of the realm of this article.

Congenital ptosis is classified as mild (2-mm ptosis), moderate (3-mm ptosis) and severe (4-mm ptosis). Levator function is classified as excellent (13 to 15 mm), very good (10 to 13 mm), good (8 to 10 mm), fair (5 to 7 mm) (Figure 1) or poor (4 mm or less). These two measurements are used to determine which surgical approach to take, with levator function being the more important of the two.

Congenital ptosis can be corrected by three operative procedures: levator resection by the skin approach, levator resection by the conjunctival approach, which includes the conjunctival Mueller’s muscle resection (Figure 2) and the Fasanella-Servat procedure, and eyebrow suspension of the eyelids (frontalis sling). The conjunctival approach is used for those patients with approximately 2 mm of ptosis, excellent levator function and a good response to neosynephrine.

The best surgical approach for congenital ptosis (excluding patients with severe ptosis and poor levator function of 4 mm or less, which requires a frontalis sling) is a levator aponeurotic or muscle resection via the skin approach. Familiarity with this approach will lead toward more consistent good results. The Table shows the amount of levator resection for a given amount of ptosis and levator function with emphasis on the levator function.

The measurement of the amount of resection of the levator aponeurosis or muscle is from the disinserted end proximal with the muscle on little to no stretch.

Surgical procedure

This is the procedure for levator aponeurosis or muscle resection.

Under general anesthesia, intubation and sterile skin preparation, the upper eyelid crease is marked at the desired height so it can be symmetrical with the opposite upper eyelid crease.

Xylocaine 1% (lidocaine HCl, AstraZeneca) with epinephrine, Marcaine 0.75% (bupivacaine HCl, Winthrop) and Wydase (hyaluronidase, Wyeth) are injected subcutaneously along the eyelid crease, as well as subconjunctivally.

The skin is incised along the methylene blue marks with a No. 15 blade. A Stevens scissors is used to buttonhole the orbicularis muscle at the superior tarsal border and extend medial and laterally the length of the tarsal plate.

The pretarsal skin and orbicularis are dissected off the upper half of the tarsal plate.

With a double-pronged skin hook pulling inferiorly on the skin-muscle flap, a Stevens scissors or high-temperature cautery is used to sharply dissect underneath preseptal skin and orbicularis superiorly in a plane underneath the orbicularis muscle and anterior to the levator muscle.

With gentle pressure on the inferior lid, the orbital septum and preaponeurotic fat are prolapsed forward.

The orbital septum is opened, and the preaponeurotic fat is prolapsed, excised and cauterized.

A double battery, hand-held cautery is used to dissect up levator aponeurosis along with Mueller’s muscle from conjunctiva as superior as necessary to accomplish the predetermined levator-Mueller’s muscle resection based upon the Table. The medial and lateral horns of levator are only cut as necessary to allow resection of the amount of levator desired.

Three double-armed 6-0 silks are placed through the anterior one-half of the tarsal plate, central, nasal and temporal, 4 to 5 mm from the superior tarsal border and back through Mueller’s muscle and the Levator muscle with the levator muscle being placed inferiorly with little stretch.

The amount of levator resection is measured from the inferior edge of the levator muscle, which is held in the forceps. The eyelid height and contour are evaluated, and adjustments are made.

The excess levator and Mueller’s muscle are excised. Two to three millimeters of skin are then excised superior to the incision before closure.

Four 6-0 chromic catgut sutures form the eyelid crease by suturing pretarsal orbicularis to levator aponeurosis. The skin is closed with a running 6-0 fast-absorbing suture as well as some interrupted sutures.

A copious amount of antibiotic ointment is applied without a Frost suture or a double patch. In the past, a 4-0 silk Frost suture was placed in the lower eyelid margin and taped to the forehead for ocular protection for 24 hours, and the eye was double patched.

Postoperatively, a bland lubricating ointment is placed in the eye four times a day for 1 week and transitioned over to artificial tears four times a day for as long as necessary for globe protection and comfort.

For more information:

• Mark R. Levine, MD, FACS, is a clinical professor of ophthalmology, Department of Ophthalmology, Case Western Reserve University. He can be reached at University Suburban Health Center, 1611 South Green Road, Suite 306A, South Euclid, OH 44121; 216-291-9770; fax: 216-291-0550.

References:

• Anderson RL, Baumgartner SA. Amblyopia in ptosis. Arch Ophthalmol. 1980;98(6):1068-1069.
• Anderson RL, Baumgartner SA. Strabismus in ptosis. Arch Ophthalmol. 1980;98(6):1062-1067.
• Levine MR. Manual of Oculoplastic Surgery. 3rd ed. Philadelphia, PA: Butterworth-Heinemann; 2003:100.
• Levine MR. Managing congenital ptosis is possible. Ocular Surgery News Europe/Asia-Pacific Edition. February 2001:39.
• Nesi FA, Lisman RD, Levine MR. Ophthalmic Plastic and Reconstructive Surgery. 2nd ed. St. Louis, MO: CV Mosby; 1998.
• Suh DW. Ptosis, Congenital [eMedicine Web site]. Available at: www.emedicine.com/OPH/topic345.htm