A longitudinal study of the biometric and refractive changes in full-term infants during the first year of life

Abstract

Changes in ocular axial dimensions and refraction were followed longitudinally, using ultrasonography and retinoscopy, during the first year of life (mean ages 4-53 weeks) of a group of 20 full-term infants (10 male, 10 female). Using a mixed-model regression analysis, axial length changes as a function of time were found to be best described by a quadratic expression (AL=17.190+0.128x-0.0013x(2), where AL is the axial length in mm and x is the age in weeks), while anterior chamber depth changed linearly (ACD=2.619+0.018x, where ACD is the anterior chamber depth in mm): lens thickness was essentially constant. Spherical equivalent refraction through most of the first year showed a steady reduction in hypermetropia (SER=2.982-0.032x, where SER is the spherical equivalent refraction in dioptres): astigmatism also tended to diminish. Mean hyperopic refractive errors through the year were negatively correlated with corresponding axial lengths (SER=12.583-0.541AL), but some individual subjects showed marked departures from this pattern. These results are discussed in relation to concepts of emmetropization.