Which of the following lists the classical Park's 3-step findings for a patient with a left superior oblique palsy?

• A. LHT in primary gaze; LHT worse in left gaze; LHT worse with right head tilt.
• B. LHT in primary gaze; LHT worse in right gaze; LHT worse with left head tilt.
• C. LHT in primary gaze; LHT worse in right gaze; LHT worse with right head tilt.
• D. LHT in primary gaze; LHT worse in left gaze; LHT worse with left head tilt.

Answer: (B)

Park's three-step test looks for (1) which eye is hypertropic in primary position, (2) the gaze that makes that hypertropia worse, and (3) the head tilt that makes it worse. For a left superior oblique palsy, the left eye sits higher in primary gaze. The left superior oblique primarily depresses the eye when it is adducted, so when the patient looks to the left, the left eye is adducted and relies on the left SO to depress it; a palsy here causes the vertical misalignment to worsen. Tilting the head to the left adds more extorsion/decompensation challenge to the left eye, further increasing the hypertropia.

Putting it together, the pattern is: left hypertropia in primary gaze; left hypertropia worse with left gaze; left hypertropia worse with left head tilt.