Underaction of the Medial Rectus Muscle Following Surgery for Squint
N.T. Strang, DipAppSc(Linc), DOBA
A.M.V. Brooks, MD, FRACO, FRACS, FRACP
W.E.Gillies, FRACO, FRACS, FRCS
A series of twenty-three cases of underaction of the medial rectus muscle following surgery for esotropia was investigated.
Of these, four showed marked underaction (24º or less adduction,) eight moderate underaction (25º adduction) and eleven mild underaction (30-34º adduction). Factors associated with medial rectus underaction were:
- Large or multiple recession of the medical rectus beyond the oculomotor equator.
- A significant vertical component e.g. V or A sign, superior oblique tendon sheath syndrome.
- Diminished adduction of the fellow eye.
Prevention of gross medial rectus underaction needs careful design of surgery using A Scan and measurement of amplitude pre operatively especially in the presence of a significant vertical component.
