Session: Poster session C

The oculomotor imbalance in the absence of visual input in case of persistent concomitant strabismus

The oculomotor imbalance in the absence of visual input in case of persistent concomitant strabismus.

Introduction: The components of the muscular imbalance often appear more complex after one or several muscle surgeries for a concomitant strabismus than they initially do. Thus, the MRI of the orbits could provide useful data if a new surgery is indicated. This procedure is now systematically applied to optimize the surgical strategy.

Methods: The MRI of the orbits was performed according to an appropriate protocol with axial, coronal, standard and oblique, and sagittal oblique sections in SEpT1 and SEpT2 sequences (without Gadolinium). It was carried out with closed eyes, i.e. without visual input, thus revealing the imbalance of the global passive and active muscles forces. 

Patients: Sixty-two patients with a persistent concomitant strabismus (either residual, repeated, consecutive or complex) were examined according to usual strabismological procedures, completed with the realization of an MRI.

Results: The persistent strabismus that appeared after a surgery for an esotropia was a persistent or repeated esotropia or a consecutive exotropia. If it originated after a surgery for an exotropia, the strabismus was a persistent or repeated exotropia or a consecutive esotropia. In both cases a residual or additional incomitant deviation may be associated. The deviation was confirmed by the MRI. It showed the imbalance of the global muscle forces. Nonetheless, the deviation appeared either of the same type as the manifest deviation, or of the opposite type or side, or differently on both eyes. Therefore, the surgical strategy in order to treat the persistent strabismus was to correct the imbalance of this forces. The postoperative results are analyzed in detail.

Conclusion: The imbalance of the global muscle forces on which the visual input acts is to be assessed. It is to be corrected by a new surgery and the forces shared optimally between the muscles involved.