Arguing with success: Pulley surgery versus conventional surgery for convergence excess esotropia

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I nthe strabismus literature, introduction of an innovative new surgical procedure typically takes the form of a retrospective case series in which good results are taken as validation of the procedure. The paper byMitchell and Kowal in this issue of the Journal of AAPOS, showing excellent results from bilateral medial rectus muscle recessions and pulley posterior fixation for convergence excess esotropia, follows this model. But does this success prove the utility of adding pulley posterior fixation to medial rectus muscle recessions? Experience has shown that medial rectus muscle recessions alone, in conventional amounts targeting the distance deviation with full cycloplegic correction, produce a high rate of undercorrection. Various methods of augmenting the conventional amount of surgery have been advocated to reduce the number of undercorrections and eliminate the dependence on bifocals for adequate near alignment. These have included operating for the near deviation, the mean of the distance deviation with and without correction, the mean of the near deviation with and without correction, a prism-adapted angle, or a systematic adjustment of the surgical dosage table. The concern about this approach is that, if enough surgery is performed to correct the near alignment, an exotropia with distance fixation may result. Although a few exotropias are reported, this is not a major problem in either the short term or after many years of follow-up.Moreover, the target angle thatMitchell and Kowal used was the mean of the distance and near deviations with correction—they were therefore also performing augmented medial rectus muscle recessions. The principal reason for adding pulley posterior fixation sutures in this group of patients is to reduce the distance– near incomitance (convergence excess). Scleral posterior fixation sutures have been advocated for this purpose and pulley posterior fixation sutures are thought to be functionally similar. But although scleral posterior fixation sutures reduce the distance–near incomitance when used by themselves, they do not necessarily provide additional effect when combined with medial rectus muscle recessions. This may seem paradoxical if the