Clinical features
All 3 forms of monocular elevation deficiency are characterized by hypotropia of the involved eye with limited elevation, a chin-up head position with binocular fusion in downgaze, and ptosis or pseudoptosis (Fig 11-6). True ptosis is present in 50% of affected patients. These are features of third nerve palsy, as well. Therefore, if any other feature of third nerve palsy is present, that condition should be suspected rather than monocular elevation deficiency.
The clinical features of each form of monocular elevation deficiency are as follows:
In support of this classification, studies using magnetic resonance imaging 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 inferiorly is present, the inferior rectus muscle should be recessed. 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 eliminated.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.