Abstract
Purpose: :
To investigate the correlations in astigmatism between siblings at different ages between 1 and 14 years
Methods: :
Refraction data were available starting in infancy for 116 children with at least one sibling. In families with more than two children, only data from the two oldest were included. All children were refracted in the laboratory by non-cycloplegic near retinoscopy until the age of 3 years and by non-cycloplegic distance retinoscopy thereafter. Only the right eye data were used. Astigmatism was decomposed into crossed-cylinder components J0 (main axis) and J45 (oblique). The correlations in J0 and J45 between siblings were evaluated by the Pearson correlation coefficient.
Results: :
Overall the mean J0 +/- SD was -0.087 (0.368) at 1 year, -0.030 (0.181) at 5 years, -0.006 (0.266) at 10 years and -0.009 (0.266) at 14 years, indicating a shift to less against the rule astigmatism and less variability after infancy. Correlations in J0 between siblings were significantly greater than zero at one year (r = 0.254, p = 0.006), 10 years (r = 0.253, p =0.007) and 14 years (r = 0.22, 0.045), but not at 5 years (r = -0.008, ns). For J45, the mean +/- SD was -0.02 (0.169) at 1 year, -0.013 (0.105) at 5 years, -0.015 (0.095) at 10 years and -0.016 (0.135) at 14 years. The correlations in J45 between siblings were low and not statistically significant at all ages.
Conclusions: :
The correlation in J0 between siblings dropped between 1 and 5 years and then rose after 5 years. As we reported previously, a similar trend was found in the correlations of spherical equivalent refraction (SER) between siblings from 1 to 14 years. The similar pattern shown for J0 and SER between siblings suggests that there is a familial link in refractive error including main axis astigmatism.
Keywords: astigmatism • refraction • refractive error development