CHAPTER 11

Vertical Deviations

A vertical deviation can be a heterotropia or a heterophoria (see Chapter 2). A vertical tropia is described according to the resting position of the deviating nonfixating eye. Thus, if the right eye is higher than the left and the left eye is fixating, the deviation is termed a right hypertropia. If the right eye is lower than the fixating left eye, it is called a right hypotropia. If the ability to alternately fixate is present, the deviation is usually named for the hyperdeviating eye. In the case of a vertical heterophoria, the deviation is, by convention, termed according to the hyperdeviating eye. Thus, a vertical phoria in which the right eye is higher than the left eye is termed a right hyperphoria.

Surgical treatment of these conditions is discussed in Chapter 14.

A Clinical Approach to Vertical Deviations

In diagnosing a vertical deviation, a useful first step is to analyze the relationship between the elevators and the depressors of the 2 eyes. In the case of a right hyperdeviation, 1 of 4 situations can arise when the left eye is covered and the right eye is forced to fixate, depending on the innervational relationship between the eyes. The specific scenario is determined by the final position of the nonfixating left eye once the cover is removed:

1.The innervation to the depressors of the right eye is matched in the left eye, leading to a left hypotropia of a magnitude similar to that of the original right hypertropia. This is termed a “true” vertical tropia.

2.The left eye does not adopt a lower position but remains in the same position. This may reflect a violation of Hering’s law of motor correspondence (see Chapter 5), confirming the presence of a unilateral (right) dissociated vertical deviation (DVD). (DVD is discussed in more detail later in this chapter.)

3.The left eye rises under the cover, leading to a left hyperdeviation when the cover is removed. This situation also seems to violate Hering’s law and represents a bilateral DVD, also termed a double hyperphoria.

4.The left eye adopts a hypotropic position under the cover but not to the same degree as the original hypertropia of the right eye. This can represent a combination of a true vertical tropia and a dissociated component (DVD) or, alternatively, a primary versus secondary deviation due to a restriction or palsy (see Chapter 5).

To simplify the discussion, the combined form (situation 4) is not addressed in this chapter. If the patient has a true hypertropia, a few principles aid in confirming the diagnosis:

1.A hyperdeviation that is incomitant in the horizontal plane suggests an oblique muscle disorder, while a comitant one is more consistent with a vertical rectus problem.