The authors present the effects of the tenotomy and reattachment procedure on a patient with accommodative strabismus and fusion maldevelopment nystagmus syndrome (FMNS) who did not require strabismus correction. The ocular motility study of this patient allowed the opportunity to assess the isolated effects of pure 4-muscle T&R procedure on FMNS waveforms and to compare the resulting improvement to those predicted by both model simulation and INS-based analysis. Data and model predicted results concurred. T&R produced improvement in FMNS waveforms similar to those in INS across a broader field of gaze and reduced the Alexander’s law variation. Nystagmus acuity function (NAFX) plots after surgery versus gaze angle were higher and had lower slopes than preoperatively. Parents reported considerable improvement in functional abilities.