Müller’s muscle is an important component of the upper eyelid levator mechanism; however, the primary lid elevator is the levator palpebrae superioris (LPS), which originates from the lesser wing of sphenoid and inserts into the superior aspect of the tarsus and orbicularis oculi and its overlying dermis. The LPS has two lamellae and the anterior one forms the aponeurosis inserting into the tarsus and orbicularis, while the posterior one forms Muller’s muscle. Muller’s muscle is under involuntary control with sympathetic innervation. It adds a few millimeters of lift to the eyelids and its dysfunction is associated with acquired ptosis, although it is not the main cause of this. The LPS and Muller’s muscle develop from the superior rectus (not superior oblique muscle) embryologically. The other muscle that is clinically relevant to eyelid ptosis is the frontalis muscle, as this is the primary brow elevator and thus also an elevator of the upper eyelid skin. Ptosis of the brow itself can result in drooping of the eyelids into the visual field, although frontalis dysfunction is not a cause of eyelid ptosis specifically. Overactivity of the frontalis can sometimes assist in compensating for genuine eyelid ptosis.1–3
2. McCord CD Jr, Codner MA, eds. Eyelid and Periorbital Surgery. St Louis, MI: Quality Medical Publishing; 2008
3. Jubbal KT, Kania K, Braun TL, Katowitz WR, Marx DP. Pediatric Blepharoptosis. Semin Plast Surg 2017;31(1):58–64 TRUE VERSUS PSEUDOPTOSIS OF THE EYELID 2. It is important to be able to differentiate between true ptosis and pseudoptosis of the upper eyelid. Which one of the following clinical scenarios would be considered an example of true upper eyelid ptosis? Upper eyelid ptosis is known as blepharoptosis and is defined as a drooping of the upper eyelid margin to a position that is lower than normal. The normal position for the upper eyelid to rest when upright and in forward gaze is around the level of the upper limbus in the midpupillary line. Apparent drooping of the eyelid can be either true ptosis, as caused by dysfunction of the levator mechanism, or another cause, which is described as pseudoptosis as it is not a primary levator mechanism problem. CN III is the main nerve involved with innervation of the levator mechanism of the upper eyelid and therefore a palsy of this nerve would leave to significant ptosis. A patient with enophthalmos after facial trauma may have one eyelid sitting lower than the other because the globe is sitting in a larger space than on the other side (i.e., the orbital space is increased), so the soft tissues fall further over the eyelid. In a patient with contralateral exophthalmos, the eyelid will also appear lower on the index side, but this is due to abnormal elevation on the contralateral side, as the soft tissues have further to reach. Blepharospasm can give the appearance of a lowered upper lid due to unwanted contractions of orbicularis oculi. Patients with Grave’s disease may have unilateral lid retraction, which also gives the appearance of a contralateral ptosis. They may also have lagophthalmos on downward gaze known as “Von Graef’s sign.”1–4
4. McCord CD Jr. The evaluation and management of the patient with ptosis. Clin Plast Surg 1988;15(2):169–184 CONGENITAL BLEPHAROPTOSIS 3. You see a 6-month-old infant in clinic. His parents are concerned about the appearance of his left eye, as the upper lid sits lower on this side, partially covering the iris. He is otherwise healthy and developing normally. Which one of the following is true of his condition? Congenital ptosis is due to developmental dysgenesis of the LPS muscle. It is usually noticed shortly after birth and can be unilateral or bilateral, with a slight predominance for occurrence on the left. It is most often a sporadic, isolated occurrence and does not have a clear inheritance pattern. It has been associated with dominant, recessive, and X-linked cases as well as rare syndromes. Because the levator is poorly formed and fibrosed, upper lid excursion is usually reduced and the supratarsal crease is absent or elevated. Other physical findings include a decreased palpebral aperture, a reduced margin to light reflex, and lagophthalmos on downward gaze. The condition is not usually progressive, so is unlikely to become worse over time.1,2
Acquired ptosis may be classified as myogenic, neurogenic, traumatic, or mechanical. Involutional ptosis is the most common type of acquired ptosis. It represents a subtype of myogenic ptosis and is caused by stretching of the levator aponeurosis attachments to the tarsal plate. Dermal attachments remain in place. Traumatic causes are the next most common, where there is disruption of the levator aponeurosis. These can be secondary to cataract surgery, due to use of hard contact lenses, or due to blunt trauma to the eye leading to soft-tissue swelling. Neurogenic causes include CN III palsy and Horner’s syndrome, as the latter will cause weakness to Muller’s muscle. Mechanical causes tend to refer to external physical causes that counteract normal lid elevation, such as upper lid tumors and excess upper eyelid skin (dermatochalasis).1–3
Differentiation between congenital and acquired causes of blepharoptosis is usually straightforward, given the timing of symptoms. In the event that the diagnosis is less obvious, it may be useful to differentiate between the two, based on the presence or absence of lagophthalmos on downward gaze. This occurs secondary to levator fibrosis which is more commonly seen in congenital cases. Strabismus refers to a misalignment of the eyes as a result of impaired extraocular muscle function. Amblyopia is a lazy eye where there is decreased vision secondary to abnormal visual development during infancy. Telecanthus is an increase in distance between the medial canthi. The interpupillary distance remains normal. Hypoglobus is downward displacement of the eye in the orbit and may give the appearance of ptosis. None of these features specifically help differentiate between congenital and acquired ptosis, although many of them can be associated with congenital ptosis.1–5
This patient is likely to have dehiscence of the LPS. The other options may all lead to ptosis, but an elevated fold and supratarsal hollowing are classic signs of levator dehiscence. Botulinum toxin inadvertently placed into the levator during treatment of glabellar or forehead rhytids can lead to isolated temporary brow or eyelid ptosis. Keeping injections high in the brow and superficial can help minimize this. Reduced sympathetic innervation could reduce Müller’s muscle function leading to a subtle ptosis in conjunction with meiosis and anhidrosis (Horner’s syndrome). This can occur secondary to tumors at the lung apex, or within the neck or spine. Myasthenia gravis is a systemic autoimmune neuromuscular disorder which can cause diplopia with ptosis that is typically worse toward the end of the day. Patients can also have problems with facial movement, swallowing, and speaking. Compression of CN III can cause loss of levator function, also leading to an isolated ptosis.1–3
When assessing patients for surgical correction of blepharoptosis, an assessment should be made of levator function (Fig. 111.1). The amount of lid elevation is graded as mild (>10 mm lift), moderate (5–10 mm lift), or severe (0–5 mm lift), and this is the most important factor in determining surgical management. Naturally, this will be linked to the cause of the ptosis. For example, if there is good elevation in the presence of ptosis, the levator mechanism is probably elongated or stretched. Other factors which are important in surgical planning include the degree of ptosis and lid height position, which are essentially the same thing. The duration of ptosis is not usually relevant, other than if sudden onset which may suggest a traumatic cause. Lagophthalmos is often present in congenital ptosis. Furthermore, it is highly likely to occur after ptosis surgery and can exacerbate dry-eye symptoms.1,2
There are a number of surgical procedures available for the correction of upper eyelid ptosis,1 but at present there have been no randomized controlled studies comparing the effectiveness of these techniques. McCord et al2 proposed a treatment algorithm for blepharoptosis based on levator function (see Fig. 111.1). According to this, the patient could have either resection or advancement procedures. Levator advancement is useful for mild to moderate ptosis and requires good levator function with an aponeurotic defect. It involves a blepharoplasty type skin incision and dissection to the aponeurosis which is sutured to the tarsus to elevate it. A patient with more than 10 mm of levator function would probably have a formal aponeurotic repair or Müllerectomy, and a patient with less than 5 mm of levator elevation would probably be a candidate for frontalis suspension. More recently, Chang et al3 have undertaken a systematic review of blepharoptosis studies and proposed a treatment algorithm more specifically for involutional blepharoptosis, which would also advocate the use of an advancement procedure for this patient. According to this algorithm (Fig. 111.2), a patient with minimal to moderate ptosis and good levator function would be a candidate for Müller’s muscle–conjunctival resection. PATIENT WITH BLEPHAROPTOSIS Evaluate levator function >10 mm function usually involutional Aponeurotic repair 5-10 mm function usually congenital/myogenic Levator resection or advancement <5 mm function usually congenital/traumatic Frontalis suspension Fig. 111.1 Algorithm for ptosis repair. PATIENT WITH INVOLUTIONAL PTOSIS Determine the degree of ptosis and verify good levator function Minimal-moderate ptosis General anesthesia Local anesthesia Posterior MMCR Any other adjunctive plastic surgery procedures (e.g., blepharoplasty) Moderate-severe ptosis Local anesthesia Levator advancement Adjunctive procedures under local anesthesia Fig. 111.2 Algorithm for treatment of involutional ptosis. (MMCR, Müller’s muscle–conjunctival resection.)
correct? Lagophthalmos is very likely to occur following correctional surgery for eyelid ptosis; so, patients must be advised about this risk and its potential postoperative management prior to undergoing surgery. The secondary problems of lagophthalmos include corneal exposure, keratitis, and dry-eye syndrome. Treatment includes daytime eye drops and night time ointments and patching. When undertaking ptosis correction surgery, care must be taken to avoid overcorrection or undercorrection. The use of epinephrine can increase the sympathetic tone to Müller’s muscle; so, slight overcorrection may be required to take this into account. When using local anesthetic agents, the levator muscles may be paralyzed, so undercorrection may be required. Although a general anesthetic avoids difficulties with patient compliance, where possible, local anesthetic is preferable because it allows assessment of lid position during surgery. Undercorrection of ptosis will necessitate revision surgery to further elevate the eyelid, and overcorrection is usually managed nonoperatively in the first instance by early stretching and massage. If it does not settle with time, surgical revision may be indicated. Schirmer’s test is performed to assess for the presence of dry eye. It involves placing a Schirmer paper strip into the eye for 5 minutes and wetting on the strip is then assessed at the end of the 5-minute period. Patients who regularly wear contact lenses are unlikely to suffer from dry eyes, so this test is not typically indicated for them.1
The Fasanella-Servat technique is used for mild cases of blepharoptosis in patients with excellent levator function. It involves a transconjunctival approach and thereby avoids a skin scar, but the outcomes can be unpredictable. It is a resection technique, not an advancement technique, and involves removal of Müller’s muscle, part of the tarsus and levator, and the conjunctiva. It can result in a floppy upper lid as a result of the tarsal resection. Many modifications and variations of the technique have been described since its first description in 1961.1–4
The gapping method is useful for achieving correct advancement when patients undergoing levator aponeurosis advancement or external levator resection are under general anesthesia. The preoperative excursion measurement (9 mm in this case) is used as a guide to set advancement so that the distance between the upper and lower eyelids matches the excursion measurement. Levator aponeurosis advancement is indicated for mild to moderate ptosis and is undertaken using a skin incision at the desired supratarsal fold rather than a transconjunctival approach. The upper lid is set according to excursion such that with good excursion, as in this case, the upper lid should be set just below (not just above) the upper limbus. Only if the excursion was poor, should the lid be set above the upper limbus. In general, a 4:1 ratio of advancement to ptosis correction is required with this technique. Therefore 12 mm of levator advancement (not 6 mm) would probably be needed to achieve correction of the 3-mm ptosis. Although a central lifting suture is used initially to secure the levator to the superior tarsus, this is not sufficient by itself and therefore an additional two sutures are placed, one medial and one lateral to the central suture. In addition, supratarsal crease fixation may be performed (see Fig. 111.2).1–3
Frontalis suspension can provide 1 cm of excursion with a good result in a straightforward gaze but will likely produce lagophthalmos during sleep. Therefore, nighttime patching and ointment will be required to protect the globe. The main indication for this surgery is congenital blepharoptosis with poor excursion, so it is an appropriate technique in this scenario. This surgery does not involve resection of Müller’s muscle. This is part of the Putterman conjunctival technique and the external levator resection techniques as described by Beard and Burke, respectively. Suspension is not achieved by direct suturing, instead it requires slips of fascia lata, other fascia, or similar tissue to suspend the upper eyelid to the frontalis (see Fig. 111.4). Bilateral suspension is often required, even where there is a unilateral ptosis, in order to achieve good symmetry.1–3
The levator muscles receive bilateral equal innervation. The presence of severe ptosis on one side will create an impulse for bilateral lid retraction. If, as in this case, a patient undergoes unilateral correction, the innervation for lid retraction decreases, leading to ptosis on the nonoperated side. This is described in Hering’s law. Hering’s test should therefore be performed preoperatively to avoid this occurrence; this involves immobilizing the brow and having the patient maintain a straightforward gaze. The affected upper eyelid is then gently elevated using a cotton-tipped applicator to alleviate the ptosis. The presence of contralateral ptosis should then be assessed. 1,2 Putterman and Fasanella are both names associated with blepharoptosis surgical techniques, not tests. Schirmer’s test is for the evaluation of tear production.3,4