Changes in Ocular Refraction in the Strabismic Child:A Longitudinal Study

Abstract

The characteristics of refractive development in the strabismic child are investigated in this thesis. The children involved were all hospital out-patients, their ages ranging, initially, from a few months to approximately twelve years. Each was examined on at least two occasions, cycloplegics being used. Changes in mean sphere, astigmatism and anisometropia have been analysed in relation to age, sex, refractive and strabismic state, strabismic angle, spectacle correction and treatment. Refractive changes in strabismic children are characterised by a high incidence of hypermetropic increases, particularly in the first six years of life. This contrasts with non-strabismic developments found in other studies, where the main shift was towards emmetropia and myopia. The most significant changes occur in the first six years, although these are most marked in the first three. Environmental factors, such as surgery and spectacle correction, appear to be involved to a greater extent during this period than in subsequent periods. Sex differences were small. During the first four or five years, females are, if anything, rather more developed, refractively, than males. Maturity appears to be the causative factor. The results indicate that hypermetropic increases are a normal feature of refractive growth, even in non-strabismic children. The high incidence in strabismic children, however, suggests that such changes may be indicative of a predisposition to the development of strabismus. There is increasing evidence to indicate that refractive changes are not necessarily linked to axial elongation, and that axial length may decrease during ocular growth. The results add weight to the view that emmetropization is an outdated concept. The outstanding need is for a longitudinal study, commencing at birth, to establish the exact nature of the relationship between strabismic and non-strabismic patterns of refractive development. The findings may have a bearing on the management of the strabismic child.