Vertical offsets of horizontal recti muscles in the management of A and V pattern strabismus

Vertical transposition of the horizontal rectus muscles is the preferred operation in cases of A and V pattern strabismus in which oblique muscle dysfunction is inadequate to merit oblique surgery. Fifty‐nine patients undergoing standard horizontal surgery with half tendon width vertical offsets and eight patients undergoing two‐thirds to full tendon width offsets were retrospectively studied. Technique for pattern measurement and surgery are discussed. Postoperative data were analysed on a short‐term (less than six weeks) and long‐term (greater than 12 months) basis. Standard horizontal surgery combined with half‐tendon width vertical transposition is shown to be an effective operation for collapsing all subgroups of A and V pattern strabismus when indications are appropriate. The initial correction to within ± 10 D of pattern was 96% over all with 78% remaining collapsed to within ± 10 D over an average 36‐month follow‐up: Recess‐resect, bimedial and bilateral rectus recession operations with offsets are all approximately equally effective in pattern collapse. A graded pattern collapse response was found with greater collapse being related to greater initial pattern. The risk of conversion, from a more desirable pattern (AET, VXT) to a less desirable pattern (AXT, VET) is low (7.3%). For patterns >30 D, three quarters to full‐tendon width offsets were effective in collapsing pattern. For A and V patterns with significant oblique muscle dysfunction, oblique surgery is advocated.