Torsional changes in surgery for A-V phenomena.

The role of torsion in the aetiopathogenesis of A-V phenomena has not been sufficiently emphasized. The success of vertical displacement of horizontal recti in correction of A or V has not been attributed to torsional changes. To evaluate this aspect, 21 cases of A or V phenomena were subjected to monocular recession-resection procedure with vertical shifting. Preoperative and postoperative torsional changes were evaluated on synoptophore (subjective torsion), and confirmed by fundus photography (objective torsion). Intorsion with A phenomenon was seen preoperatively in 5 of 8 cases which increased after surgery and was seen postoperatively in the other 3 cases also. Extorsion was observed in 5 of 13 cases pre operatively in 'V' phenomenon, but the changes in extorsion after surgery were less dramatic than those in intorsion. The oblique overactions were reduced in cases where they were present. Correction of A-V phenomena by torsion induced by vertical shifting of horizontal recti muscles is proposed, highlighting the role of torsion in A-V phenomena.