| Feature | Congenital Unilateral SOP | Congenital Bilateral SOP | Acquired Unilateral SOP | Acquired Bilateral SOP |
| Head Posture | Tilt to Unaffected Side | Chin Down | Tilt/Face Turn to Unaffected Side (to overcome diplopia) | Chin Depression |
| Facial Asymmetry | Present (reduction of distance between lateral canthus & corner of mouth on side of head posture) | Absent (unless also unilateral) | Absent | Absent |
| Vertical Deviation (Hypertropia) | Large hyperphoria (often >20 PD) Manifest with head straight Increases on near fixation | Alternating hypertropia of non-fixing eye | Hypertropia on Affected Side Worse on Adduction | Reversal of hypertropia on right/left gaze & dextro/laevodepression |
| Horizontal Deviation | Generally none (primary vertical) | Constant large V-pattern esotropia (≥25 PD) | Generally none (primary vertical) | V-pattern esotropia |
| Bielschowsky Head Tilt Test | Positive | Positive to either side with reversal of hypertropia on right & left tilt (differentiates from primary ET with IOOA) | Positive (fixation at 3m target) | Positive to either side |
| Excyclotorsion | Present in primary position (fundus exam) | Present in primary position (fundus exam) | Present, but often symptomatic excyclotorsion >10° in primary position | Symptomatic excyclotorsion >10° in primary position (most pronounced feature) |
| Vertical Fusion Amplitude | Large (≥10 PD) | Large (≥10 PD) | Small (2–3 PD) | Small (2–3 PD) |
| Key Clinical Pearls | Childhood onset, long-standing adaptation | Bilateral SOP often suspected with large V-pattern ET and chin down. | Sudden onset of diplopia, often after trauma or ischemic event. Less adaptive. | Often due to trauma. Most debilitating diplopia, especially torsional. |
| Fundus Examination | Essential to confirm excyclotorsion | Essential to confirm excyclotorsion | Useful to confirm excyclotorsion | Essential to confirm excyclotorsion |