Associated incomitance in concomitant strabismus. Diagnosis and surgical treatment

The motor deviation in concomitant strabismus may be accompanied by horizontal, vertical and/or torsional incomitance that hinders the development of binocularity. This should be corrected together with the horizontal deviation or in a repeat surgery.

A series of seventeen patients suffering from a major form of incomitance A or V pattern eso- or exotropia was investigated clinically. Incomitance was measured in all directions of gaze, horizontally, vertically and, as far as possible, torsionally. In 8 cases magnetic resonance tomography of the orbits was performed and has shown in particular,the position of the insertion of the lateral recti, relative to that of the medial recti. All the patients underwent surgery. Clinical, radiological and intra-operative data were concordant in all cases.

All possible clinical forms or any combination thereof could be defined with precision and corrected according to the motor disorder of each case. After surgery the A or V pattern was reduced to 4° or less in all cases. The vertical deviation was corrected at least between 25° right and left gaze in all cases but 3.

The most appropriate surgical strategy for the individual clinical form can be determined. The"triple procedure"includes the shift to the horizontal meridian of the insertion combined/or not with a slanted recession or plication of the lateral rectus, and the recession of the overacting oblique muscles. It enables us to correct in a single surgery both horizontal and cyclo-vertical incomitance.

The correction of associated incomitance significantly improves motor and angle dependent sensory results in the management of concomitant strabismus.