A calculator proposal for estimating refractive error after 3
years using the onset biometric values in primary school children: a
cohort study
ABSTRACT
Aim
To evaluate consecutive measurements of the biometric parameters, age,
and refraction error in a Turkish population at primary school age.
Materials and Methods
A total of 197 children aged between 7-12 years were included. The data
of three consecutive measurements of children, who were examined at
least once a year for three years using both cycloplegic
auto-refractometry and optical biometry, were used in this retrospective
study. Spherical equivalent <-0.50D was considered to be
myopic; >+0.75D was considered to be hypermetropic. Age,
gender, body mass index, spherical equivalent, axial length, anterior
chamber depth, central corneal thickness, keratometry, and lens
thickness were analyzed. The onset data obtained in 2013 whereas, the
final data were from 2015. Logistic and Cox regression analyses
were performed (p<0.05).
Results
The mean of the onset and the final spherical equivalents were 0.19D
(0.56), and 0.08D (0.80), respectively. The myopia prevalence was
increased among refractive errors in observation periods (univariable
analysis p=0.029; multivariable analysis p=0.017). The onset axial
length (HR:4.55, 95%CI:2.87-7.24, p<0.001), keratometry
(HR:2.04, 95%CI:1.55-2.67, p<0.001) and age (HR:0.73, 95%CI:
0.57-0.92, p=0.009) correlated myopia progression. To calculate the
estimated spherical equivalent, the onset data were included in the
logistic regression model. The onset data of spherical equivalent
(β=0.916, p<0.001), axial length (β=-0.451,
p<0.001), anterior chamber depth (β=0.430, p=0.005) and
keratometry (β=-0.172, p<0.001) were found to be significantly
associated with the mean SE at the final data.
Conclusions
To calculate the estimated spherical equivalent following three years,
an equation was proposed. The estimated refractive error of children can
be calculated by using the proposed equation with the associated onset
optical parameters.
Key words: Axial length; Biometry; Biometric Calculator;
Myopia; Refractive error; Spherical equivalent