Other Incomitant Vertical Tropias
Several other hypertropias are not oblique muscle disorders yet may present with incomitance. These include innervational problems, such as the upshoots and downshoots seen in Duane retraction syndrome and partial third nerve palsy; and mechanical disorders, such as Brown syndrome, thyroid eye disease, orbital tumors, and orbital implants (eg, glaucoma drainage devices, scleral buckles). These topics are discussed elsewhere in this volume and in other BCSC Sections.
Comitant Vertical Tropias
Comitant vertical tropias commonly exhibit a hypertropia or a hypotropia that does not change significantly when gaze is shifted from one side to the other.
Monocular Elevation Deficiency
Monocular elevation deficiency (previously termed double-elevator palsy) involves a limitation of upward gaze with a hypotropia that is similar in adduction and abduction. This motility pattern may be caused by restriction of the inferior rectus muscle or by an innervational deficit (weakness of 1 or both elevator muscles or a monocular supranuclear gaze disorder). Patients may have a combination of a restriction and elevator muscle deficit.
Clinical features
Monocular elevation deficiency features a hypotropia of the involved eye that increases in upgaze, a chin-up position with fusion in downgaze, and ptosis or pseudoptosis (Fig 11-5). True ptosis is present in 50% of patients. If any other feature of third nerve palsy is present, that condition should be suspected rather than monocular elevation deficiency.
Figure 11-5 Monocular elevation deficiency of the left eye. Top row, No voluntary elevation of the left eye above horizontal. Second row, Hypotropia of the left eye across the horizontal fields of gaze. Third row, Depression of the left eye is unaffected. Bottom left, Ptosis (true and pseudo-) of the left upper eyelid during fixation with the right eye (in the top 3 rows, the left upper eyelid is elevated manually). Bottom center, Persistence of ptosis and marked secondary overelevation of the right eye during fixation with the left eye. Bottom right, A partial Bell phenomenon, with the left eye elevating above the horizontal on forced eyelid closure.
Clinical features of the 3 forms of monocular elevation deficiency are as follows:
restriction
positive forced duction on elevation
normal elevation force generation and elevation saccadic velocity (no muscle paralysis) often an extra or deeper lower eyelid fold on attempted upgaze
poor or absent Bell phenomenon
elevator muscle innervational deficit
free forced duction on elevation
reduced elevation force generation and saccadic velocity
preservation of Bell phenomenon (indicating a supranuclear cause) in many cases
combination
positive forced duction on elevation
reduced elevation force generation and saccadic velocity
In support of this classification, studies using MRI have shown either focal thickening of the inferior rectus muscle, supporting a restrictive etiology, or normal ocular motor nerves, suggesting a central unilateral disorder of upgaze.
Management
Indications for treatment include a large vertical deviation in primary position, with or without ptosis, and an abnormal chin-up head position. If restriction originating from below the eye is present, the inferior rectus muscle should be recessed, using an adjustable suture if possible. If there is no restriction, the medial and lateral rectus muscles can be transposed toward the superior rectus muscle (Knapp procedure). Alternatively, the surgeon can recess the ipsilateral inferior rectus and either recess the contralateral superior rectus muscle or resect the ipsilateral superior rectus muscle. Ptosis surgery should be deferred until the vertical deviation has been corrected and the pseudoptosis component removed.
Kim JH, Hwang JM. Congenital monocular elevation deficiency. Ophthalmology. 2009;116(3):580–584.
Orbital Floor Fractures
Clinical features and management of orbital floor fractures are discussed in Chapter 27 and in BCSC Section 7, Orbit, Eyelids, and Lacrimal System. The discussion in this chapter focuses on motility abnormalities in patients with these fractures.
Clinical features
Diplopia in the immediate postinjury stage is to be expected and is not necessarily an indication for urgent intervention. Depending on the site of the bony trauma, muscles can be either entrapped and restricted or paralyzed due to nerve damage. Palsy of a muscle may resolve over several months. If the fracture requires surgery, the range of eye movements may improve. On the other hand, fibrosis after trauma may cause restriction to persist even after successful repair of the fracture.
Management
Treatment of strabismus is usually needed when diplopia persists in primary position or downgaze or there is an associated compensatory head position. Some mild limitations of eye movements can be managed with prisms.
Planning of eye muscle surgery depends on the fields where diplopia is present and on the relative contributions of muscle restriction and paresis. For a nonresolving hypotropia in primary position (Fig 11-6), recession of the ipsilateral inferior rectus muscle can be effective, especially if the muscle is tight on forced-duction testing. Similarly, an incomitant esotropia (with diplopia on side gaze) due to restriction on the medial side may be improved by recession of the ipsilateral medial rectus muscle.