Background To compare objective torsion, measured using fundus photography, and subjective torsion, measured with the Lancaster red-green test (LRGT) or double Maddox rod test (DMRT), in patients with acquired unilateral superior oblique palsy (SOP).

Methods Full ophthalmic examinations, including the alternate prism and cover test, ductions/versions, three-step test, LRGT, DMRT and fundus photography, were performed in 35 consecutive patients (28 men and 7 women) (mean age, 50.4±16.2 years) with acquired unilateral SOP. The correlation between the amount of torsion measured with fundus photography, the LRGT and DMRT was analysed using linear regression analyses.

Results The LRGT, DMRT and fundus photography revealed extorsion in 16 (46%), 21 (91%) and 35 eyes (100%), respectively. There were no significant correlations between the amounts of torsion measured with the LRGT, the DMRT and fundus photography. There was a statistically significant correlation between SOP duration and the amount of torsion only when measured by the LRGT (p=0.0006).

Conclusion Objective extorsion may be found in all patients with acquired unilateral SOP, whereas subjective extorsion may be found in most patients with acquired unilateral SOP; the latter was detected more frequently with the DMRT than with the LRGT.