Based on some prior studies by Weiss10 and Morax et al11- 12 in patients with craniofacial anomalies, I calculated the effect that ocular torsion may play in contributing to A and V patterns, as well as to the overelevation or overdepression seen in adduction in patients with oblique muscle overaction.13 For example, if a patient has a V pattern with inferior oblique muscle overaction, each eye will be extorted. This will rotate the insertions of the rectus muscles counterclockwise in the right eye and clockwise in the left eye. The change in force vector resulting from this rotation will create an abducting force from the superior rectus muscles and an adducting force from the inferior rectus muscles, which will contribute to the V pattern. In addition, the new positions of the insertions of the horizontal rectus muscles will make the medial rectus muscles partial elevators in adduction and the lateral rectus muscles partial depressors in abduction. This will accentuate the overelevation seen in adduction (Figure 1 and Figure 2). I calculated that for the average amount of torsion observed in a series of patients with A and V patterns, these new force vectors were substantial. The extorsion seen in patients with V patterns will cause the new force vector of each rectus muscle to be approximately equal to 24% of its original force, eg, an abducting force of the superior rectus muscle, elevating force of the medial rectus muscle, and similar changes in the lateral rectus muscle and inferior rectus muscle. The converse occurs with intorsion accompanying A patterns. Although these calculations were made before the recognition of orbital pulleys,9 and hence are probably not quantitatively accurate, they should be qualitatively valid. In a publication in 1994, Guyton and Weingarten14 carried this hypothesis an important step further by hypothesizing how the disruption of fusion that occurs with horizontal strabismus may result in a free-wheeling torsional drift of the eyes. This sets the stage for the development of A or V patterns as well as overelevation or overdepression in adduction. Later, Miller and Guyton15 confirmed this hypothesis in patients who lost fusion after strabismus surgery. However, although I conceptualized that ocular torsion was merely a contributing factor to A and V patterns, as well as overelevation or overdepression in adduction, others describe this as the major causative factor.14 Which of these differing hypotheses is correct can have important practical clinical implications in choosing a surgical plan to treat some patients. Specifically, when addressing A or V patterns, should the surgical plan take into account the vertical and horizontal actions of the operated-on muscles, or is treating torsion sufficient?