(heterotropia) n. squint: abnormal alignment of the two eyes. The strabismus is most commonly horizontal – convergent strabismus (or esotropia) or divergent strabismus (exotropia) – but it may be vertical (hypertropia, in which the eye looks upwards, or hypotropia, in which it looks downwards). In rare cases both eyes look towards the same point but one is twisted clockwise or anticlockwise in relation to the other (cyclotropia). Usually strabismus is concomitant, i.e. the abnormal alignment of the two eyes remains fairly constant, in whatever direction the person is looking. Strabismus acquired by injury or disease is usually incomitant, i.e. the degree of misalignment varies in different directions of gaze. See also cover test; deviation; divergence; heterophoria.... strabismus
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