It is useful to test oculomotility (smooth pursuit eye movements) for a whole range of reasons but in particular when a patients presents with diplopia, there are symptoms such as eye pain when looking away from the primary position of gaze and when there is a reading difficulty which is unlikely to be explained by the onset of presbyopia.
The alternating cover test in the primary position allows comparison of the primary and secondary angles of deviation. Repeating the alternating cover test in the extreme positions of gaze will cause the size of the dissociated deviation to increase in the direction of the affected muscle(s).
Interpupillary distance is the distance measured in millimetres between the centres of the pupils of the eyes. This measurement is different from person to person and also depends on whether the patient is looking at distance or near. Consideration of interpupillary distance helps ensure that len...
The trial frame has to be adjusted for an appropriate vertex distance, inter-pupillary distance and it ensure it sits straight on the nose and comfortably behind the ears. The patient must be looking through the centre of the lens.
