Natural history and associations of dissociated vertical divergence.

One hundred patients with dissociated vertical divergence (DVD) have been followed up for an average of 7.3 years. In contrast to some other reports, none of them has worthwhile binocular vision. There has been a constant association with nystagmus, often manifest, and the DVD has always been noted later than the nystagmus. In no case has the degree of DVD decreased significantly with age. The dissociation has only rarely caused a serious cosmetic problem, and then it has been markedly asymmetrical and has been improved by combined superior rectus recession and Faden procedure. DVD can simulate inferior oblique overactions, but is more commonly associated with an A phenomenon, and can be distinguished by careful cover/uncover testing. The common occurrence of associated congenital defects, especially of the central nervous system, is noted.