Diagnostic and therapeutic problems in nystagmus.

In all forms of dysfunction of ocular motility the ultimate aim in obtainin% an understanding of the nature of the condition is to try and provide some form of treatment. This has beenl achieved in most types of strabismus with the considerable advances which have been made in overcoming the sensory and motor complications of the squint, but few such advances have been made in the treatment of nystagmus, and it is important, therefore, in any symposium which is concerned with the use of prisms in the treatment of disorders of ocular motility, to take due regard of their role as one of the therapeutic measures in nystagmus even if this proves to be of very limited value. There is, however, a fundamental difference between the problems of squint and those of nystagmus occurring in young children, because squint is most commonly an isolated event whereas nystagmus is usually a manifestation of some underlying disorder, even in the socalled "idiopathic" cases. It follows that all cases of nystagmus must be assessed carefully before embarking on a line of treatment which is concerned with the nystagmus alone. It is the purpose of this paper to discuss the nature of I 20 cases of nystagmus which have been examined recently at the Hospital for Sick Children, Great Ormond Street, and at Moorfields Eye Hospital, High Holborn, in children under the age of 6 years, and to indicate the possible merits and limitations of treatment of cases of nystagmus with prisms.