34 Pseudoptosis: Evaluation and Management
Abstract
This chapter discusses the diseases and conditions that result in the perceived appearance of blepharoptosis without abnormality of the levator muscle. These periocular disorders result in manifestations mimicking ptosis including decreased vertical palpebral fissure height, deep superior sulcus, and elevated upper eyelid crease. The chapter discusses conditions causing pseudoptosis such as dermatochalasis, vertical strabismus, contralateral eyelid retraction, enophthalmos, ocular abnormalities, and protractor overaction.
34.1 Introduction
Pseudoptosis describes a group of periocular disorders that resemble blepharoptosis but are not due to primary levator muscle abnormality. Pseudoptosis often results from underlying changes in the size or position of the eye and orbital contents, but can also include problems with the periocular muscles of protraction. This chapter will describe common conditions associated with pseudoptosis and explore factors important for evaluation and management.
The manifestations of true blepharoptosis due to abnormality or dehiscence of the levator muscle include decreased vertical palpebral fissure height, deep superior sulcus, and elevated upper eyelid crease. The entities that create pseudoptosis mimic these physical signs but have causes other than retractor muscle dysfunction. Most commonly, pseudoptosis is secondary to the perceived appearance of a decrease in palpebral fissure height while the margin reflex distance (MRD1) is normal. This phenomenon is often present bilaterally, as is seen with dermatochalasis causing excess skin to obscure the eyes. Additionally, a relative decrease in palpebral fissure height in comparison to the contralateral eye can create this effect. Pseudoptosis can also be present when there is presence of a deep superior sulcus or elevated upper eyelid crease. Pseudoptosis may also be secondary to overaction of the muscles of protraction as in hemifacial spasm or benign essential blepharospasm.
34.1.1 Dermatochalasis
Most commonly, pseudoptosis is secondary to the perception of a decrease in palpebral fissure height. The most frequently encountered underlying abnormality is dermatochalasis. Excess upper eyelid skin obscures the palpebral fissure; giving the appearance of a decreased MRD1 while the underlying lid function is preserved. Lifting the eyelid skin reveals normal palpebral fissure height (Fig. 34.1). Surgical management of dermatochalasis and mechanical ptosis has been extensively discussed in Section II.
34.1.2 Vertical Strabismus
Evaluation of ptosis should always include thorough assessment of the relative positions of the globes as well as extraocular muscle function. Misalignment of the eyes, as in vertical strabismus, may lead to a pseudoptosis due to close relationship between the upper eyelid and globe position. As the superior rectus muscle and levator muscle are closely linked, the upper eyelid can follow the malpositioned globe and create the appearance of ptosis. An ipsilateral hypotropia, where an eye is deviated downward in comparison to the fellow eye, can decrease the palpebral fissure height due to the lid following the globe inferiorly (Fig. 34.2). This phenomenon, which is seen in conditions such as monocular elevation deficiency, can be assessed by occluding the fellow eye and observing a return of the pseudoptotic lid to normal position with fixation. 1 By a similar mechanism, the presence of a contralateral hypertropia can give the appearance of ptosis if the patient fixates with the hypertropic eye. Pseudoptosis resulting from such eye misalignment is often corrected by strabismus surgery.
34.1.3 Contralateral Eyelid Retraction
Patients presenting with unilateral or asymmetric eyelid retraction may be first thought to have ptosis of the contralateral eye (Fig. 34.3). This phenomenon is due to the appearance of a relatively lower MRD1 in comparison to the retracted eyelid. Investigation of the etiology of eyelid retraction is important in these cases of pseudoptosis. The most common cause of eyelid retraction is thyroid eye disease, but other causes can include dorsal midbrain syndrome, aberrant regeneration of the facial nerve, and scarring or fibrotic changes of the upper eyelid. Treatment of pseudoptosis due to these conditions focuses on therapy for the underlying disorder and recession of the retracted eyelid.
Patients with thyroid eye disease may also exhibit overuse of the muscles of protraction in an attempt to improve symptoms of corneal exposure and discomfort associated with eyelid retraction. 2 This overaction of the corrugator and procerus muscles can lead to glabellar rhytids, medial brow ptosis, altered brow contour, and further eyelid asymmetry. 3 In these cases, treatment with botulinum toxin chemodenervation of the glabellar muscles may improve brow position and eyelid symmetry. 3
34.1.4 Enophthalmos
The increase in orbital volume or decrease in ocular volume creates the clinical appearance of ptosis by changes in the palpebral fissure height, deepening of the superior sulcus, and elevation of the eyelid crease. A variety of conditions can create this appearance, but enophthalmos is the most common. Enophthalmos, or posterior displacement of the globe within the orbit, can result from traumatic, degenerative, neoplastic, or involutional changes of the bony structures and contents of the orbit. Recognition and evaluation of these causes is important to treatment of both the periorbital manifestations and underlying disease. Evaluation of enophthalmos should include detailed history of trauma and systemic disease, full ophthalmic assessment, exophthalmometry, and radiographic imaging. It is important to distinguish true enophthalmos from relative asymmetry due to contralateral exophthalmos. Each specific mechanism of enophthalmos requires varied management and intervention.
Orbital Fracture
While blunt trauma can lead to ptosis from direct damage to the levator muscle or cranial nerve III, trauma can also lead to the development of pseudoptosis. Fractures of the orbital bones can increase the effective orbital volume causing posterior displacement of the globe, thereby leading to consequent changes of the upper eyelid position. Fractures of the medial wall and floor of the orbit are more likely to cause enophthalmos than the lateral wall or roof of the orbit. 4 Patients presenting with ptosis after trauma should have a tailored examination to investigate the orbital anatomy including assessment of motility and exophthalmometry, which is the measurement of the distance from the corneal apex to the lateral orbital rim. Radiographic imaging with orbital computed tomography (CT) is necessary to view the orbital bones and position of the globe (Fig. 34.4). Enophthalmos is more likely in cases of large (>50%) floor fractures or combined floor and medial wall fractures. 5 ID#b452a023_6 – 7 In cases of traumatic enophthalmos, the restoration of normal orbital volume by fracture repair and/or orbital volume augmentation can correct the position of the globe and resolve pseudoptosis. Orbital fractures should be repaired in cases of early manifest enophthalmos, symptomatic diplopia, or in cases of large orbital floor fractures causing significant latent enophthalmos or hypoglobus. 8
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