Examination, registration and analysis of clinical expressions of DVD.

The clinical appearance of dissociated vertical deviation (DVD) can be modified by the presence of other vertical deviations. This may be one of the reasons of relatively late diagnosis (sometimes even only after a first strabismus operation). If the DVD is not recognized preoperatively, this can lead to unexpected failure of the strabismus operation, with cosmetically unacceptable vertical deviations. The key to early diagnosis is a meticulous observation with special attention to differences in vertical deviations on right and left eye fixation in primary position and in levo- and dextroversion, using the alternating cover test. This is relatively easy and non-invasive. The authors propose a method for registration and analysis of the results. This method leads in most cases to a reliable diagnosis of the different components of the vertical deviation. The authors illustrate this method in 82 patients. In the large majority, the method presented allowed them to evaluate the respective importance of each component. Their sample illustrates convincingly the wide variety of clinical expressions of DVD. Only six patients presented a DVD without associated vertical deviations. In many cases the DVD was less important than the associated vertical deviations. This explains the difficulty of diagnosis of DVD in many cases.