A test called the Bielschowsky Darkening Wedge Test can be used to reveal and diagnose the presence of<unk> , although any (or no) amount of dissociative occlusion may also prompt it to occur. The patient is asked to look at a light. One eye is covered and a filter is placed in front of the other eye. The density or opacity of this filter is gradually increased, and the behaviour of the eye under the cover (not of the eye beneath the filter) is observed. Initially, if<unk>  is present, the covered eye will have elevated, but as the filter opacity is increased the eye under the cover will gradually move downwards. This Bielschowsky phenomenon is present in over 50% of persons with prominent<unk> , all the more if the<unk>  is asymmetric and amblyopia is present as well. The Bielschowsky phenomenon is also present in the horizontal plane in patients with prominent DHD<unk>  horizontal<unk> . Differential diagnosis<unk>  is often mistaken for over-action of the inferior oblique extra-ocular muscles.<unk>  can be revealed on ocular movement testing when one eye is occluded by the nose on lateral gaze. This eye will then elevate, simulating an inferior oblique over action. However, in a unilateral case, overaction of the superior rectus muscle in the unaffected dominant eye, can also be a causing factor as well as causing a V pattern exophoria.
Dissociated vertical deviation
Infantile esotropia
Lipoatrophia semicircularis
Cyclotropia
Ecotropism
Ectopia cordis
Exotropia
Pseudostrabismus