J Korean Ophthalmol Soc.  2018 May;59(5):471-477. 10.3341/jkos.2018.59.5.471.

Correlations among Refractive Error, Axial Length, and Corneal Power in Childhood

• Lee YG
• Baek SH
• Lim HT
• Kim DH

• KMID: 2411456
• DOI: http://doi.org/10.3341/jkos.2018.59.5.471

Abstract

PURPOSE
To investigate sexual differences and correlations among refractive error, axial length (AL), and corneal power.
METHODS
A retrospective review of the medical records for 2,006 eyes of children aged 5-16 years was conducted. Cycloplegic refraction and AL measurements were performed on all eyes. Sexual differences in corneal power and AL were investigated in emmetropic eyes and after adjustment for the spherical equivalent (SE). The distribution of AL with every 1 diopter (D) interval was determined. Quantitative correlations among SE, corneal power, and AL were analyzed using multiple regression analyses.
RESULTS
The mean age of the subjects was 7.62 years and the mean SE was −0.10 D. Males had a longer AL and lower corneal power than females both in emmetropic eyes and in all subjects after adjustment for the SE. The AL increased 0.40 mm for every −1 D change of the SE. When compared to a 1 D interval of the SE, the AL difference between the upper and lower values of a 95% confidence interval was 2.98 mm, which showed the variability of the AL distribution. Eyes with a long AL had lower corneal power (p < 0.001). Every 1 mm change of AL resulted in a −2.1 D change in the SE, and every 1 D change of corneal power resulted in a −0.8 D change in the SE (p < 0.001).
CONCLUSIONS
The distribution of the AL and corneal power was variable, even in eyes with the same refractive error. The AL and corneal power differed by sex. Quantitative correlations between the SE, AL, and corneal power can be clinically used in the estimation of these parameters.

Keyword

Axial length; Childhood; Corneal power; Eye model; Refractive error

MeSH Terms

Child
Female
Humans
Male
Medical Records
Refractive Errors*
Retrospective Studies

Figure

• 

  Figure 1. Box-and-Whiskers plot for the distribution of axial length according to spherical equivalent (inverted X-axis). Box denoted interquartile range (IQR, 25th–75th percentile) of axial length for a specific spherical equivalent value. Whiskers denoted 1.5 × IQR, and dots denoted outliers. A horizontal line and a diamond in a box denoted median and mean value of axial length, each. N = number of subjects; AL = axial length; CI = confidence interval.

• 

  Figure 2. Correlation among ocular parameters and refractive parameters. (A) Definite negative correlation between spherical equivalents (inverted X-axis) and axial length was noted. (B) Weak correlation between mean keratometer and spherical equivalent (inverted Y-axis) was noted. (C) Definite negative correlation between mean keratometer and mean deviation of axial length in the same refractive error group.

Reference

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