Axial length and Axial length/Corneal Curvature percentiles for Chinese cohort aged 4 to 18 years

Abstract

Purpose : To establish percentile curves for axial length (AL) and axial length/corneal curvature (AL/CR) by age and determine the influence of gender in Chinese children and young adults.

Methods : Retrospective analysis of data on AL, cycloplegic spherical equivalent (SE) and corneal curvature of 14127 Chinese participants aged 4 to 18 years from 3 studies conducted in Shanghai, China. AL and AL/CR percentiles were estimated using Lambda-Mu-Sigma method and compared for agreement using intra-class correlation (ICC). Logistic regression was used to model the risk of myopia based on age and percentiles. Area under ROC curve was used to compare model predictability.

Results : For the 14127 participants (9.4±4.0 yrs, Males 54%), SE was -0.76±2.53D (-13-+9D), AL was 23.7±1.4 (18.3-30.4 mm), CR was 7.85±0.25 (7-9.5 mm). Myopia (≤-0.5D) was present in 42.3% and increased with age. ICC between AL and AL/CR percentiles was moderate (ICC=0.575), low in younger children (ICC=0.19, 4yrs) and steadily increased with age (ICC=0.78, 17yrs). The 10, 50, 90 and 97th percentiles for AL and AL/CR at 4, 6, 10, 15 and 18 yrs are listed in the table. For AL, males were at a higher percentile compared to females (61^st / 34^th , 53^rd / 41^st , 49^th / 44^th percentiles at ages 4,10 and 18 years respectively). However with ALCR, gender differences reduced (55^th / 45^th , 51^st / 48^th , 47^th / 48^th for males / females) at ages 4, 10, 18 years respectively. A greater separation by gender was evident at younger ages for both AL and AL/CR. Logistic model based risk of myopia resulted in 94% and 97% area under ROC curve for AL and AL/CR, respectively. Compared to AL/CR, AL percentiles predicted a higher risk of myopia at 18 yrs for those in the lower percentiles. By 18 yrs, AL & AL/CR percentiles ≥10 were associated with a >66% and >50% risk of myopia respectively, while percentiles ≥75 were associated with a ≥40% & ≥31% risk of high myopia.

Conclusions : Age and gender specific percentiles provide reference data for monitoring refractive errors in children aged 4 to 18 years from China. Furthermore, AL/CR percentiles may predict the probability of myopia better than AL.

This is a 2020 ARVO Annual Meeting abstract.

 

AL and AL/CR percentile chart