In lateral rectus (LR) paralysis the amount and type of surgical repair is guided by knowledge of the amount of active LR force which has returned and the amount of antagonist medial rectus (MR) contracture which has occurred. Active LR force is assessed directly by holding the eye as it attempts following or saccadic movements and indirectly by observation of horizontal saccadic velocity. These new active force tests are more reliable than electromyography in assessing mechanical paralysis. Medial rectus contracture is a limit of rotation range but is not a general stiffening of the antagonist. Hummelsheim transplantation operations are indicated when severe LR paralysis and little MR contracture exist. Otherwise, horizontal recessresect surgery is preferable. Simultaneous superior oblique paralysis commonly creates a "V" pattern. Increased horizontal surgery amounts are then indicated.
Scott AB. Active Force Tests in Lateral Rectus Paralysis. Arch Ophthalmol. 1971;85(4):397-404. doi:10.1001/archopht.1971.00990050399001