Abstract
Purpose: :
To assess the relationship between anthropometric measures, and spherical equivalent refraction and ocular biometry in 12 year old Australian students.
Methods: :
The Sydney Myopia Study randomly selected 55 primary and secondary schools and invited all students in Years 1 (mean age 6.7) and 7 (mean age 12.7) to participate. Cycloplegic (1% cyclopentolate) autorefraction was performed, and axial length (AL) and corneal radius (CR) were measured using the IOLMaster (Carl Zeiss, Germany). Spherical equivalent refraction (SER) was calculated (sphere +½ cylinder) for the right eye only. Height (freestanding SECA height rod, Model 220) and body weight (Model TBF-300, Tanita) were measured using a standardised protocol.
Results: :
Of the 2353 Year 7 students who participated (75.3% response rate), 2300 are included in this analysis and 49.1% were girls. The mean SER for boys was +0.58D (95% confidence interval, CI, 0.51 - 0.65) and girls +0.39D (95% CI 0.30 - 0.47). Boys on average were neither significantly taller (156.3mm, 95% CI 155.8 - 156.8) nor weighed more (49.8kg, 95% CI 49.1-50.5) than girls (156.0mm, 95% CI 155.7 - 156.4 and 49.8kg, 95% CI 49.1-50.5, respectively). However, boys had longer AL (23.58mm, 95% CI 23.54 -23.63), anterior chamber depth (3.58mm, 95% CI 3.57 -3.60) and larger average CR (7.83mm, 95% CI 7.82 -7.85) than girls (23.17mm, 95% CI 23.12 -23.22, 3.47mm, 95% CI 3.45 -3.48 and 7.73mm, 95% CI 7.71 -7.74, respectively). Pearson correlation of SER with age and weight was not significant (p = 0.06 and p = 0.26, respectively), however, SER was negatively correlated with AL (-0.61, p <0.0001) and height (-0.08, p = 0.0003). After controlling for age, the Pearson partial correlation still showed a negative correlation of SER with AL (-0.61, p <0.0001) and a negative but weak correlation with height (-0.07, p = 0.0013).
Conclusions: :
In the younger cohort from the Sydney Myopia Study, no significant correlation between SER and height was reported. In this older cohort there is a weak correlation of SER and height. This contrasts with data from Singapore, where a correlation of SER and height was reported in children, but was not found in adults.
Keywords: refractive error development • myopia • clinical (human) or epidemiologic studies: natural history