Abstract
Purpose :
In existing literature, refraction progression has been studied simply as progression rate or fitted into predefined statistics models. In the present study we attempt hypothesis-independent analysis to investigate the patterns in refraction growth process in Chinese children, and to explore the possible risk factors affecting the different components of progression as defined by Principal Component Analysis (PCA).
Methods :
The first-born twins (n=637) in Guangzhou Twin Eye Study with 6-year annual visit data (baseline age 7-15 years) were used for this analysis. A partitioning clustering method was conducted to group similar growth patterns in first-born twins. Principal component analysis (PCA) was performed to extract the main differences in how refraction evolves over time. Main outcome measures were clustering groups identified by cluster analysis, components deconstructed with PCA and the regression coefficients of risk factors for PCA scores.
Results :
First, Cluster 1 to 3 were classified after a cluster analysis, representing stable, slow and fast progressing patterns of refraction respectively. Baseline age, baseline refraction, paternal refraction, maternal refraction and proportion of two myopic parents showed significant differences across the three groups. Second, a PCA was conducted to extract three major components of progression: ‘Average refraction’, ‘Acceleration’ and the combination of “Myopia stabilization” and “Late onset of refraction progress”. Younger children with higher level of myopia were associated with larger ‘Acceleration’. In regression models, change of height and weight, near work time, parental myopia were correlated with ‘Acceleration’, while female gender, change of height and weight were associated with ‘Stabilization’.
Conclusions :
Genetic and environmental risk factors have different impacts on patterns of refraction progression. The acceleration of refraction progression was associated with near work and parental myopia, while stabilization of refraction was related to gender as well as the change of height and weight. Outdoor time was related to the later onset of myopic shift.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.