Periorbital Surgery - Clinical Tree

Key Points

1.
Detailed knowledge of eyelid and orbital anatomy is crucial for any physician working in the periocular area.
2.
There are a variety of surgical approaches to the orbit. The best choice depends on the size and location of the pathologic process.
3.
Rejuvenation of the periocular area is best accomplished using a combination of neuromodulators, fillers, and surgical procedures.
4.
The Asian eyelid differs from the Western eyelid. When performing blepharoplasty, careful surgical planning and clear patient expectations are necessary to achieve a satisfactory outcome.

Pearls

1.
The seven bones that make up the orbit are the sphenoid, maxillary, ethmoid, lacrimal, zygoma, palatine, and frontal.
2.
From anterior to posterior, the layers of the upper eyelid above the lid crease are as follows: skin, orbicularis oculi, orbital septum, preaponeurotic fat, levator aponeurosis, Müller’s muscle, and conjunctiva.
3.
Levator function is the most important variable in determining what type of ptosis surgery to perform.
4.
When closing a full-thickness eyelid defect, either the anterior or posterior lamella must be vascularized to remain viable; therefore only one lamella may be repaired with a free graft.

Questions

1 Name the seven bones of the orbit.

Sphenoid, maxillary, ethmoid, lacrimal, zygoma, palatine, and frontal.

2 What are the distances of the anterior ethmoid foramen, posterior ethmoid foramen, and optic canal from the orbital rim?

This can be remembered by the mnemonic 24-12-6. The anterior ethmoid foramen is approximately 24 millimeters posterior to the orbital rim on the medial wall, the posterior ethmoid foramen is an additional 12 millimeters posterior, and the optic canal is a further 6 millimeters posterior.

3 What are the eyelid lamellae?

The eyelid is often conceptualized as consisting of an anterior and a posterior lamella. The anterior lamella is composed of skin and the striated muscle fibers of the orbicularis muscle. The posterior lamella is composed of the tarsal plate and the palpebral conjunctiva. The anterior and posterior lamellae are separated by the orbital septum (the “middle” lamella).

4 An object travels through the upper eyelid 12 millimeters superior to the lid margin. What structures does it travel through?

In the upper eyelid, the tarsus is typically not taller than 10 millimeters. Therefore at 12 millimeters the object will travel above the tarsus. The layers from anterior to posterior are the skin, orbicularis oculi, orbital septum, preaponeurotic fat, levator aponeurosis, Müller’s muscle, and conjunctiva. Below 10 millimeters, the object would travel through the anterior and posterior lamellae, as defined above.

5 What is the difference between dermatochalasis, blepharoptosis, and blepharochalasis?

Dermatochalasis refers to excess skin on the upper eyelid. When severe, it can hang down over the upper eyelid lashes and obstruct the superior visual field. Blepharoptosis refers to drooping of the eyelid, often due to levator dysfunction. Blepharochalasis is a rare syndrome in which episodic edema causes distortion and discoloration of the upper eyelid. Its etiology is poorly understood, but it is commonly considered to be a type of localized angioedema.

6 How is dermatochalasis surgically addressed?

Dermatochalasis repair is achieved via blepharoplasty. In this procedure, excess skin and occasionally orbicularis muscle are excised. If there is excessive preaponeurotic or orbital fat (herniation of the medial fat pad is commonly seen), it may be excised or sculpted to optimize lid contour by opening the orbital septum.

7 How is blepharoptosis repaired?

The two most common methods to repair blepharoptosis are external levator advancement (ELA) and internal levator advancement (ILA). ELA involves a skin incision at the lid crease, whereas ILA is a transconjunctival approach involving excision of variable amounts of conjunctiva, Muller’s muscle, levator, and tarsus. When levator function is poor, such as in congenital ptosis, the upper eyelid can be tethered to the frontalis muscle to assist in eyelid elevation. This procedure is known as a frontalis sling.

8 The contralateral eyelid occasionally falls after unilateral blepharoptosis repair. Why does this happen?

Hering’s law of equal innervation postulates that yoke muscles receive equal innervation. According to this law, innervation to the bilateral levator palpebrae superioris muscles is equal, and when one eyelid is ptotic the innervation increases in an attempt to clear the visual axis. The increased innervation to the contralateral eyelid can result in pseudoretraction. After repair of unilateral blepharoptosis, the drive to elevate the lids is decreased and descent of the contralateral eyelid may occur.

9 What next steps are indicated in the treatment of biopsy-proven basal cell carcinoma of the lower eyelid?

Lower lid basal cell carcinoma should undergo complete excision with frozen sections to confirm clear margins. Alternatively, patients can be referred to a Mohs surgeon for excision.

10 What principles should be kept in mind when planning the reconstruction of an eyelid defect?

Important principles include avoiding vertical tension and maintaining a good vascular supply. Minimizing vertical tension helps to avoid eyelid retraction. When a full-thickness defect is present, only one lamella can be repaired with a free graft. If both the anterior and posterior lamellae are replaced with free grafts, the rate of failure is high due to lack of blood supply.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here