In previous chapters we discussed types of strabismus where the deviation of the eyes is horizontal, inwardly or outwardly. Less frequently, strabismus may relate to vertical positions, which means that one eye is higher (hypertropia) or lower (hypotropia) from the eye that’s fixed on an object.
Vertical strabismus is generally not consistent which means that the angle of the eyes is increased or decreased depending on their position.
Most children are able to counteract diplopia by tilting their head in such a position that the eyes are aligned. As the deviation itself is often difficult to grasp, this is the first point that parents notice and that leads them to a pediatrician or an ophthalmologist.
The important types of vertical deviations are the inferior oblique hyperfunction, the superior oblique hyperfunction and the disconnected vertical deviation.
The movement of the eye caused by the lower oblique oculomotor muscle is upwards and inwardly (nasally).
The unbonded vertical deviation, also known as DVD (Dissociated Vertical Deviation), is the phenomenon of the upper rotation of the eye when it is covered.
The V phenomenon is mainly seen in the bilateral hyperfunction of the lower oblique muscles, while the phenomenon A in the hyperfunction of the bilateral...