3 Steps(Parks Bielschowsky) Test

The 3-Step Parks-Bielschowsky Test is a valuable method used to evaluate ocular motility and assess for neurological disorders affecting eye movement. It involves three key steps: observing the patient’s eye movements while performing specific head positions and eye rotations. The test helps in diagnosing conditions like gaze palsies, nystagmus, or other abnormal eye movements. By assessing the eye’s response to various positions, healthcare professionals can determine if the issue is related to a neurological problem or a more localized ocular condition. This simple yet effective test provides valuable insights into the patient's eye health and neurological function.

Parks-Bielschowsky Test for Hypertropia and Superior Oblique Palsy

Step 1: Identify the Hypertropic Eye

• Primary Position: Determine which eye is hypertropic (elevated) when the patient is looking straight ahead. For example, if there is right hypertropia, the right eye is higher than the left.
• Muscle Weakness: This suggests potential weakness in the depressor muscles of the right eye (inferior rectus or superior oblique) or the elevators of the left eye (superior rectus or inferior oblique).

Step 2: Evaluate Hypertropia with Eye Gaze

• Gaze Directions: Check whether the hypertropia worsens or improves when the patient looks to the right or left.
• Vertical Rectus Muscles:These muscles have their strongest vertical action when the eye is abducted (looking outward).
• Oblique Muscles: These muscles have their strongest vertical action when the eye is adducted (looking inward).

Step 3: Assess Hypertropia with Head Tilt

• Head Tilt Observation: Determine if the hypertropia changes with right or left head tilt.
• Right Head Tilt: This causes the right eye to intort (due to the superior oblique and superior rectus muscles) and the left eye to extort (due to the inferior oblique and inferior rectus muscles).

Superior Oblique Palsy Diagnosis

Effect of Head Tilt:

• In a healthy individual, tilting the head engages the superior oblique and superior rectus muscles of the eye closest to the shoulder to maintain eye level, while the inferior oblique and inferior rectus muscles stabilize the other eye.
• In superior oblique palsy, the superior rectus muscle’s action is not counterbalanced by the weakened superior oblique muscle, resulting in vertical deviation of the affected eye when the head tilts towards that side. There is no deviation when tilting towards the unaffected side because the superior oblique muscle is functional in the unaffected eye.

Symptoms and Observations:

• Double Vision: Patients with superior oblique palsy often experience double vision. This condition typically improves or resolves when tilting the head towards the shoulder of the unaffected side, while tilting towards the affected side exacerbates the double vision due to increased separation of images.

Conclusion:

• Diagnosis: A discrepancy in ocular deviation based on the direction of head tilt suggests unilateral superior oblique muscle palsy, commonly due to damage of the trochlear nerve.
• For precise diagnosis and treatment, it is recommended to consult with an eye care specialist or neurologist.