Figure 6.

Lateral view of schematic horizontal rectus extraocular muscle (EOM) and pulley in supraduction. Before surgery (left), distance D₂ from globe center to insertion is maintained equal to distance D₁ from pulley to globe center. For a small angle of supraduction α typical of the ocular motor system, the rotational velocity axis imposed on the globe by the EOM tilts posteriorly by angle α/2. In the absence of globe translation, recession of the EOM’s scleral insertion (right) reduces its distance D₂ from globe center without significantly altering distance D₁ from pulley to globe center. After recession, supraduction to angle α causes the EOM’s rotational velocity axis to tilt posteriorly by less than angle α/2, with the actual amount depending on the recession distance. Globe translation would further alter the EOM’s rotational axis.