Dissociated vertical deviation (DVD for short) is a special form of eye misalignment in which one eye drifts upward involuntarily. This upward deviation typically appears when the affected eye is not actively used for vision, such as during covering or when tired. DVD is one of the most common vertical strabismus forms in childhood.
In DVD, one eye slowly drifts upward and turns slightly outward. When the eye is "switched on" again, for example by removing the cover, it slowly returns to its normal position. A characteristic feature of DVD is that it can affect both eyes, but often asymmetrically, meaning more pronounced on one side than the other.
Unlike other vertical strabismus forms, DVD does not follow the usual laws of eye motility: the partner eye does not move downward in the opposite direction (as would be the case with a "true" vertical deviation).
The exact cause is not fully understood. However, we know that:
The diagnosis is made by the pediatric ophthalmologist using special cover tests. In the so-called alternating cover test, the doctor observes whether one eye comes down from above when uncovered. In addition, visual acuity, refraction, and overall eye motility are examined.
Mild DVD without significant cosmetic impact or amblyopia does not necessarily require treatment. Regular check-ups are nevertheless important.
If there is accompanying amblyopia, it is treated, independently of the DVD, with glasses and/or patching (occlusion).
For prominent DVD, surgery on the eye muscles is the only effective treatment. Typically, the superior rectus muscle (musculus rectus superior) is weakened to reduce the upward deviation. The procedure can be performed on one or both eyes.
Important: Eye exercises or vision training cannot correct DVD. The cause lies in faulty processing in the brain, not in muscle weakness that could be trained away.