Clinical Examination:
Vertical Misalignments and the Diagnosis of a Superior Oblique Palsy

The vertical rectus muscles and the oblique muscles control both the vertical position of the eyes as well as the torsional position (keeping the eyes straight when the head is tilted). Depending on the position of the eyes, each muscle has a primary or secondary action as shown in the table below. Knowledge of this can aid in the determination of a paretic vertical muscle.

	Elevates Eye	Depresses Eye	Rotates Eye Inward	Rotates Eye Outward
Right Gaze	L Inferior Oblique, R Superior Rectus	L Superior Oblique, R Inferior Rectus	N/A	N/A
Left Gaze	L Superior Rectus, R Inferior Oblique	L Inferior Rectus, R Superior Oblique	N/A	N/A
Left Tilt	N/A	N/A	L Superior Rectus, L Superior Oblique	R Inferior Rectus, R Inferior Oblique
Right Tilt	N/A	N/A	R Superior Rectus, R Superior Oblique	L Inferior Rectus, L Inferior Oblique

From this table, we can see that if the right superior oblique muscle was paretic, there would be insufficient depression of the right eye in left gaze. This would lead to a right hypertropia in left gaze. Similarly, if the head were tilted to the right, the intorting and elevating action of the right superior rectus would go unopposed, and the right eye would be hypertropic in this position also.

The Parks - Bielschowsky Three Step Test attempts to determine the paretic muscle by performing alternate cover testing in different head positions. This test only works in cases of a single paretic muscle. Since the superior oblique is the vertical muscle most commonly affected by itself, this is basically a test for dysfunction of the superior oblique.

• Step 1: Determine which eye is hypertropic. Paralysis of the superior oblique is one cause of hypertropia.

• Step 2: Determine whether the hypertropia is greater in left or right gaze. Hypertropia due to superior oblique paralysis is greater on gaze to the contralateral side.

• Step 3: Determine whether the hypertropia is greater in left or right head tilt. Hypertropia due to superior oblique paralysis is greater in a head tilt to the ipsilateral side.

 

Demonstration of a Left Superior Oblique Palsy using the
Three Step Test

Move the mouse pointer over the image (and within the box) to observe eye movements in different directions. (Browsers enabled with JavaScript, such as I.E. 4.0 or Netscape 3.0 are required to observe this.)


This demonstrates a left superior oblique palsy.
There is decreased depression of the left eye in adduction.

Step 1: Determination of hypertropia in straight ahead gaze.
This demonstrates a left hypertropia.
Step 2: Determination of hypertropia in:
RIGHT GAZE Increased hypertropia of left eye.	LEFT GAZE Minimal hypertropia.
Step 3: Determination of hypertropia in:
RIGHT HEAD TILT Mild left hypertropia.	LEFT HEAD TILT Increased left hypertropia.
Conclusion: In the above example, a left hypertropia greater in right gaze, and greater in left head tilt, fits the Three Step Test criteria for a left superior oblique palsy (or a left Fourth Cranial Nerve Palsy). Go to the Eye Motility Page. Go to Case #2 page, which discusses a Fourth Cranial Nerve Palsy.