Disorders where one eye is higher than the other often cause vertical double vision (diplopia).
Common causes include:
The situation where one eye is higher than the other. When this only occurs when one or both are covered, it is called a "hyperphoria". When it occurs even when both eyes are viewing, it is called a "hyper deviation". Hyperphoria and hyperdeviation generally refer to the situation where the cause is known.
Skew deviation refers to a vertical misalignment of the eyes of unknown cause.