Incidence of A pattern strabismus after inferior rectus recession in patients with Graves' orbitopathy: A retrospective multicentre study.

INTRODUCTION AND PURPOSE: Patients with Graves' orbitopathy (GO) may develop restricted elevation; this can lead to hypotropia, sometimes in combination with an abnormal head posture. Recession of one or both inferior rectus muscles is the first line surgery to restore eye motility in these patients. However, this may result in A pattern strabismus. This study was performed to determine the rate of occurrence of this type of incomitant strabismus and potential predictive factors. METHODS: All patients undergoing surgery on one or two inferior rectus muscles over a 10-year period were screened retrospectively for the A pattern, defined as a ≥5° difference in squint angle between the primary gaze and downgaze. The extraocular muscle thickness in patients with acquired A pattern was determined by computed tomography (CT) and compared with a control group consisting of patients randomly selected from the total cohort. RESULTS: In a total of 590 patients, surgery was performed on the inferior rectus muscle(s) during the study period; the A pattern was identified in 59 patients. Simultaneous surgery was performed on one or both medial rectus muscles in 32% of the patients. This group had significant incyclotorsion (p = 0.000) and less depression (p = 0.000) postoperatively. The mean amount of recession was 4.38 ± 1.53 mm in the A pattern group and 3.91 ± 1.37 mm in the control group (p = 0.032). The amount of depression was 50.2° ± 7.4° in the A pattern group and 57.3° ± 4.4° in the control group (p = 0.045). The inferior rectus muscle was significantly thicker in the A pattern than in the control group (p = 0.027), while there was no significant difference in the thickness of the superior oblique muscle between the two groups (p = 0.870). Of all patients with the A pattern, 47% required further surgery to achieve adequate binocular single vision. CONCLUSION: Increased preoperative inferior rectus muscle thickness and relatively limited depression could be predictors of postoperative A pattern inferior rectus recession in patients with GO. Step-by-step procedures are preferable in this surgically challenging group of patients.

Risk of torsion in superior rectus transposition surgery augmented with posterior scleral fixation sutures.

It has been reported that superior rectus transposition combined with medial rectus recession can provide as good results as transposition of both vertical rectus muscles, with no adverse effects on torsion or postoperative vertical misalignment. Further augmentation of transposition surgery can be achieved through the use of posterior fixation sutures, myopexy and botulinum toxin into the medial rectus. We report a patient with complete bilateral traumatic sixth cranial nerve palsies who underwent sequential superior rectus transposition surgery combined with medial rectus recession. The surgery was augmented with a myopexy (posterior suture joining superior and lateral recti with no scleral fixation) in the first eye and with a posterior fixation suture (with scleral fixation) in the second eye. After the second procedure, despite a significant improvement in horizontal alignment, the patient developed 15 degrees of incyclotorsion which was attributed to the scleral fixation suture. The patient underwent removal of the scleral suture and 3 months postoperatively had a significant reduction in incyclotorsion to 8 degrees; however this continued to be a barrier to fusion. Vertical rectus transposition of superior and inferior recti augmented with posterior scleral fixation sutures is one type of conventional surgery for complete lateral rectus palsy. In more recent times, it has become common to transpose the superior rectus alone along with recession of the contracted medial rectus. This procedure can also be augmented with a posterior fixation suture which may or may not be attached to the sclera. Whilst this surgery has gained popularity it is not without risk as demonstrated by our case in which transposition of the superior rectus was associated with postoperative incyclotorsion. In this case a possible explanation may be the use of a the posterior scleral fixation suture as it did not occur when no scleral fixation was used. Furthermore, removal of the posterior scleral fixation suture did reduce the torsion significantly although it did not eliminate it.

Complications of augmented superior rectus transposition in Duane syndrome. / Complicaciones de la transposición aumentada de recto superior en el síndrome de Duane.

CLINICAL CASE: A patient diagnosed with Duane syndrome underwent an augmented superior rectus transposition (SRT) to lateral rectus (LR) and medial rectus (MR) recession. Vertical, torsional deviation and diplopia were observed post-operatively. Removal of the Foster suture and superior rectus recession resolved the symptoms. DISCUSSION: SRT to LR is proposed in Duane syndrome with a favorable outcome. The benefit of SRT is open to debate. It could be an alternative for the vertical rectus transposition when MR recession has to be operated on in the same procedure, or in the immediate post-operative period, in order to decrease the risk of anterior segment ischaemia.

Torsional Diplopia.

BACKGROUND AND PURPOSE: Torsional diplopia can result in failure of fusion in an individual without a measureable strabismus. When presented with a patient with complaints of binocular diplopia, physicians and orthoptists should consider cyclovertical muscle dysfunction when the source of the complaint is not readily apparent. METHODS: A thorough review of the literature combined with the author's own personal experience in treating adult patients with strabismus was used to evaluate the different potential causes of torsional diplopia. Predisposing factors, diagnostic techniques, and strabismus diagnoses are considered. RESULTS: The most common cause of torsional diplopia is a superior oblique palsy. Other more common causes include thyroid-related orbitopathy and skew deviations. CONCLUSIONS: Torsional diplopia is a common cause of undiagnosed strabismus in the adult patient population. Proper consideration of the most common causes should be made.