In many patients with cyclovertical strabismus, the deviation differs between right and left gaze and, on the side of the greater deviation, often between upgaze and downgaze as well. In general, surgery should be performed on those muscles whose field of action corresponds to the greatest vertical deviation unless results of forced duction testing reveal contracture that requires a weakening procedure for a restricted muscle. For example, for a patient with a right hypertropia that is greatest down and to the patient’s left, the surgeon should consider either tightening the right superior oblique muscle or weakening the left inferior rectus muscle. (Tightening and weakening of the oblique muscles are discussed later in this chapter.) If the right hypertropia is the same in left upgaze, straight left gaze, and left downgaze, then any of the 4 muscles whose greatest vertical action is in left gaze may be chosen for surgery. In this example, the left superior rectus muscle or right superior oblique muscle could be tightened, or the left inferior rectus muscle or right inferior oblique muscle could be weakened. Larger deviations may require surgery on more than 1 muscle.
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.