Non-central Fixation in Squinting Children.

ACCORDING to Ciuppers (1958), about 2 per cent. of the population of Germany, France, and Switzerland suffer from unilateral amblyopia; the proportion in Great Britain is likely to be very similar. Though amblyopia resulting from ocular deviation may arise where the fixation is central, the great importance of eccentric fixation in relation to amblyopia is now generally recognized and considerable attention is being given to its diagnosis and treatment. On the continent the treatment of the amblyopia of strabismus is predominantly by pleoptic methods, and where orthoptic methods are practised they are often regarded as an adjunct to pleoptics (Gale, 1957). It is perhaps reasonable to regard this preoccupation with the treatment of non-central fixation by the continental authorities as a sequel to their long-standing approach to the problem of squint. This approach has been noticeably different from the practice in Great Britain (Ciippers, 1958), where for 25 to 30 years the correction of refractive errors, occlusion, orthoptic supervision, and operation in young children have been widely established. The treatment of the amblyopia of squint at a later age by pleoptics is very time-consuming and economically expensive, and it is obviously of importance to study the changes which occur in the fixation of younger squinting children, the factors which affect it, and its response to treatment, so that the management and treatment of non-central fixation in young children can be put on a firm basis. The continental experience in this field is not necessarily relevant to this country, where, in general, children with squint are seen and treated at an early age. The incidence of non-central fixation and its relationship to other factors in squinting children attending for the first time the Outpatient Department of the Manchester Royal Eye Hospital has been discussed elsewhere (Scully and Naylor, 1961). The overall incidence of non-central fixation was found to be 22-4 per cent. in 304 new patients with unilateral convergent squint. This percentage was found to increase progressively with an increase in the interval between the onset of the squint and attendance for examination. There was found to be a higher incidence in those patients having aniso-metropia of more than one dioptre, and a lower incidence in those having a later age at onset. The purpose of the present investigation is to extend these findings by comparing them with the incidence of non-central fixation in new patients attending a school clinic in …