Ptosis repair by external levator advancement







Table 11.1

Indications for surgery











Functional ptosis affecting vision
Cosmetically displeasing ptosis
Amblyopia in visually maturing children
Ptosis affecting prosthesis function in the anophthalmic socket


Table 11.2

Preoperative evaluation



























Prior facial surgery or trauma
Dry eye symptoms/lagophthalmos present
Quality of Bell’s phenomenon
Prior refractive surgery
Co-existent dermatochalasis and/or eyebrow ptosis
Amount of levator function
Need to avoid posterior conjunctival ptosis repair (i.e., strabismus, glaucoma filtration surgery/drainage device, cicatricial conjunctival diseases, fornix shortening)
Degree of ptosis present
Rule out myasthenia gravis
Presence of Hering’s law/contralateral ptosis
Desire for upper eyelid crease (particularly with Asian patients)
Potential for revision/asymmetry


Introduction


The normal position and contour of the eyelids must be recognized before undertaking ptosis repair. The position of the upper and lower eyelids is defined by the margin to reflex distance (MRD), which is the distance from the central corneal light reflex to the upper eyelid (MRD1) and the lower eyelid (MRD2). The definition of functional ptosis varies by source, but in general it is less than or equal to 2.5 mm. In the upper eyelid the contour of the lid is characterized by a peak that is nasal to the central corneal light reflex, while in the lower eyelid this peak is lateral ( Figure 11.1 ).


The evaluation of the ptosis patient begins with the classification of the specific subtype. Aponeurotic or involutional ptosis is the most common type and is caused by disinsertion of the levator aponeurosis. Myogenic ptosis is associated with a dysfunctional levator and can be seen with myasthenia gravis, chronic progressive external ophthalmoplegia (CPEO) and congenital ptosis. Neurogenic ptosis may be caused by cranial nerve III palsy or Horner’s syndrome. Mechanical ptosis is associated with an eyelid mass.


The MRD1, upper eyelid crease position and levator function are documented during the evaluation. Normal levator function is at least 12 mm of upper eyelid excursion. Hering’s law should be tested in cases of presumed unilateral ptosis. The ptotic eyelid is manually elevated and the MRD1 of the fellow eyelid is recorded. If the fellow eyelid falls after lifting of the ptotic eyelid, bilateral ptosis exists ( Figure 11.2 ). Failure to treat contralateral ptosis with a Hering’s response can result in a postoperative surprise. Ptosis associated with decreased levator function may be addressed by levator resection ( Chapter 14 ) or frontalis suspension ( Chapter 15 ) depending on the amount of levator function. The anterior approach, external levator advancement procedure, is ideal for patients with normal levator function and severe ptosis (MRD1 <1.5 mm). With the anterior approach, there is no conjunctival incision, which is relevant with patients who may need or have had glaucoma filtration surgery or strabismus surgery, or those with cicatricial conjunctival disease. The surgery does require patient cooperation to achieve optimal eyelid position and is not optimally performed under general anesthesia.




Preoperative Evaluation





Figure 11.1


Normal eyelid position

The normal upper and lower eyelid positions rest just inside of the corneal limbus, covering 1mm of the iris. The peak of the upper eyelid is nasal to the pupillary center while the lower eyelid is laterally peaked. With aging, there is often lateral shifting of the upper eyelid peak and this can be corrected at the time of surgery.



Figure 11.2


Test for Hering’s law

This patient presents with left-sided unilateral ptosis ( Figure 11.2A ). With manual elevation of the left upper eyelid, the right eyelid lowers ( Figure 11.2B ) owing to Hering’s law of equal innervation. The optimal treatment plan in this patient is bilateral upper eyelid ptosis repair, starting with the left side first.




Surgical Technique





Figure 11.3


Skin marking

An upper eyelid crease incision provides excellent access for external levator advancement surgery. In cases of co-existent dermatochalasis, this approach also allows the surgeon to perform concurrent blepharoplasty during ptosis repair. In cases where blepharoplasty is not indicated, the incision can be limited to the central one-third of the eyelid ( Chapter 12 ). The upper eyelid crease is marked as described in Chapters 3 and 4 . Note that the eyelid crease may be significantly elevated with advanced involutional ptosis and the crease should be marked lower on the eyelid instead of the superiorly migrated position and confirmed bilaterally. This well-camouflaged incision should be carefully marked and measured in cases where the eyelid crease is elevated or ill-defined due to levator aponeurotic dehiscence. Levator surgery is performed under local anesthesia with minimal IV sedation to ensure maximal levator effort and patient cooperation during surgery. Local anesthetic consisting of 2% lidocaine with 1:200,000 epinephrine is given in a maximum volume of 1.25–1.50ml to minimize levator weakness. Additional smaller amounts of local anesthetic can be given intraoperatively as needed.

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May 16, 2019 | Posted by in Reconstructive surgery | Comments Off on Ptosis repair by external levator advancement
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