Purpose
To determine if presence of refractive astigmatism is associated with change in spherical equivalent (SE) refractive error in children age 3 to 18 years of age.
Methods
Subjects were participants one or more NIH/NEI funded studies of visual development in Tohono O’odham children (“Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error” (CLEERE, Tucson Site), “Astigmatism and Amblyopia Among Native American Children”, “Amblyopia in Astigmatic Children: Development and Treatment”). Previous research has documented a high prevalence of with-the-rule astigmatism in this population. A baseline exam was conducted and follow-up exams were attempted at least yearly for each study. Data was combined across studies. Cycloplegic autorefraction (Retinomax Autorefractor (KPlus or KPlus2, Nikon Inc., Tokyo Japan)) was conducted at each study exam. Subject exams that met the following criteria were included in analyses: age 3 to < 19 years, right eye autorefraction confidence ≥ 8. Only subjects with at least two study exams and a minimum interval of 1 year between first and last exam were included in analyses. Analyses included only right eye data, and only data from each child’s baseline and final study exams. Linear regression analysis was conducted to determine the relation between baseline refractive astigmatism and change per year in SE refractive error with age (change is SE/fu interval). The following variables were also included: sex, baseline age, follow-up interval, baseline SE.
Results
For the 2,043 subjects who met inclusion criteria, mean age was 6.13 years (SD 2.90) at baseline and 10.70 years (SD 3.56) at follow-up, with a mean follow-up interval of 4.57 years (SD 3.28). SE tended to shift towards less hyperopia/more myopia with age in most children (Table 1). On average, there was a shift towards less hyperopia/more myopia of 0.16 D/year (Table 2). Neither of these trends varied significantly with amount of baseline astigmatism. Regression analysis yielded significant effects of age, sex, length of follow-up interval, and baseline SE on change per year in SE, but no significant effect of baseline astigmatism magnitude.
Conclusions
The results of the present study indicate that highly astigmatic children in this population are not at increased risk for development or progression of myopia.
Keywords: 677 refractive error development •
605 myopia