Divergence insufficiency

To compare the clinical characteristics of a population of patients with divergence insufficiency in the absence of associated neurologic disease to those patients with divergence insufficiency and an associated neurologic disorder.

A retrospective review of 251 patients diagnosed with divergence insufficiency and/or divergence paralysis. Clinical features include the age at onset, fusional divergence amplitudes, the size of the esodeviation, treatment offered, and the presence or absence of associated neurologic conditions. Classification into primary and secondary divergence insufficiency solely depended on the absence or presence of neurologic disorders, respectively.

The incidence of neurologic disease associated with divergence insufficiency was 17%. The average age at onset was 62 years for primary and 51 years for secondary divergence insufficiency. Nystagmus was noted in 43% of secondary divergence insufficiency patients and 0.01% of primary divergence insufficiency patients. Both groups exhibited decreased fusional divergence at distance fixation while retaining normal fusional divergence at near.

The majority of patients were classified as primary divergence insufficiency. Though this form of divergence insufficiency is neurologically benign, it may easily mask a more severe neurologic condition for which the presenting symptom is also diplopia for distance viewing only. These results show the importance of obtaining a detailed history regarding the symptoms, as well as documenting neurologic signs, particularly nystagmus, when investigating divergence insufficiency.