Abstract
Purpose: Despite the importance of optics in the development of human vision and visual functioning, few extensive, long-term studies exist on refractive changes during infancy and early childhood. However, with the emergence of portable, held-hand, non-cycloplegic autorefractors, it is now feasible to provide early normative data. Such information is vital to our understanding of optical development and for providing a basis for early vision screening. Method: Right eyes from 1325 2- to 6- year old children were attempted twice with the Welch Allyn SureSight autorefractor. Measurements were obtained without cycloplegia. Although the children were volunteers, our sample is likely representative of a general pediatric population as testing was conducted at all daycare centres in the metropolitan region, participation rates were high, and no children were excluded on the basis of ophthalmic, neurological, developmental, or systemic disorders. Results: 1251 of the children completed testing in both eyes. Based on their age at the time of testing, children were placed into age groups, each spanning a 6-month period. Results showed that mean spherical refractive error was remarkably consistent across the age span (range = +1.4 to +1.7D), as was variability. However, mean cylindrical refractive error showed a steady decline from 0.74D at 2 years to 0.50D at 6 years. Again, variability and percentile limits were relatively constant across groups Conclusions: These data provide the first extensive normative data on refractive development across the critical preschool period, as measured with the most prominent of the new generation of non-cycloplegic autorefractors. Our results imply that from 2 to 6 years of age, children show progressively less astigmatism, yet remain consistently hyperopic (about + 1.5D) across this age span. However, this hyperopic “plateau” in spherical refractive error may be short-lived, as our previous work with older children (Adams et. al., 2004) reveals a significant progression toward myopia after the 7th year of life.
Natural Sciences And Engineering Research Council of Canada/ Janeway Hospital Research Advisory Foundation.