Neurological significance of small esodeviations

A small esodeviation detected in an adult may represent an acquired event caused by a number of different mechanisms. These deviations may be comitant or incomitant, occur with or without diplopia and appear in association with other ocular or neurological findings or in isolation. The mechanisms include lateral rectus dysfunction, supranuclear gaze disturbances, anomalies in the vergence system, the influence of the near synkinesis and certain restrictive components. The presence of a small, acquired esodeviation may have neurological significance that may influence diagnosis and management decisions.1,2 Conditions such as divergence paralysis and convergence spasm are described in the classic literature with large esodeviations and obvious clinical features.3-7 They are not a common occurrence in most strabismus practices but are recognized readily when they occur. More subtle presentations of these entities are seen far more frequently and may be so small, or co-exist with other ocular findings, as to be overlooked. It is likely that with many clinical disorders like divergence paresis and convergence spasm that they present as a spectrum of dysfunction; it is the small end of that spectrum that will be discussed.