Fusion can mask the relationships between fundus torsion, oblique muscle overaction/underaction, and A- and V-pattern strabismus

Purpose To evaluate relationships between fundus torsion, A- or V-pattern strabismus, and oblique muscle over- or underaction, and to explore the influence of stereopsis on these relationships. Methods The medical records of patients with A or V patterns and/or abnormal ocular torsion seen at a single institution over nearly 30 years were retrospectively reviewed. Data collected were age, objective fundus torsion (estimated by indirect ophthalmoscopy), horizontal deviations in up- and downgaze, oblique muscle over- or underaction, and stereopsis. Results A total of 396 patients were included. A patterns were observed in 121 patients (30.6%); V patterns in 90 (22.7%). Of the A-pattern patients, 73.6% had superior oblique muscle overaction, whereas 71.1% of the V-pattern patients had inferior oblique muscle overaction ( P