Tenotomy and congenital nystagmus: a null result is not a failure, for “It is not the answer that enlightens, but the question”

Fixed point analysis of nystagmus

Motor disorders frequently contain a rhythmic component, but the associated oscillations are not usually precisely periodic. This lack of strict periodicity can make it difficult to identify the effects of experimental manipulations on the oscillation. In this report, we describe the application of a numerical technique for identifying fixed points of a nonlinear map to the recovery of underlying periodicities of the eye movement disorder of nystagmus. The technique is illustrated by application to two different types of nystagmus. In addition we use a local analysis of the behaviour at the fixed points to distinguish between different bifurcations in the two examples with changes in gaze angle. We conclude that the technique reveals consistent effects of experimental manipulations, which may be useful for quantitative characterisation of experimental and therapeutic manipulations of motor disorders.

Infantile nystagmus: current concepts in diagnosis and management

This review examines current approaches to the diagnosis and management of congenital forms of nystagmus. Emphasis is placed on diagnostic features that are amenable to clinical identification but those issues that can be addressed only with more detailed investigations, such as eye movement recording, are indicated. Non-surgical management, including prism spectacles, contact lenses and vision therapy, is discussed, as are surgical approaches. Because many aspects of congenital forms of nystagmus, particularly as experienced by patients with the condition in their normal lives, are poorly addressed in both the clinical and research literature, these limitations are also highlighted.