Significant Loss of Coordination Among Astigmatism Components in Young Chinese Adults With High Myopia.

PURPOSE

To investigate the coordination among astigmatism components, including refractive astigmatism (RA), corneal astigmatism (CA), and internal astigmatism (IA), across refractive statuses in a large cycloplegic sample of Chinese young adults.

METHODS

This cross-sectional study included 7971 undergraduate students in China. Cycloplegic refraction and ocular biometric were measured using an autorefractor and optical biometry. IA was calculated as the vector difference between RA and CA. Relationships among astigmatism components, refractive errors, and ocular parameters were analyzed using generalized additive models, smoothed curve fitting, and threshold effect analysis.

RESULTS

A total of 7315 young adults (mean age = 20.2 ± 1.5 years; 37.0% male) were included. The prevalence rates of RA, CA, and IA (≥1.0 D) were 16.4%, 36.7%, and 12.2%, respectively. RA and CA were significantly higher in the high myopia, moderate myopia, and moderate hyperopia groups compared to the emmetropia group, while IA was significantly smaller only in the high myopia group (P < 0.001). Piecewise relationships among RA, CA, and IA with refractive errors were identified. RA and CA showed a significant increase, whereas IA decreased in moderate and high myopia. Furthermore, the compensatory effect of IA was significantly reduced in the high myopia group.

CONCLUSIONS

The components of astigmatism demonstrated coordination from low myopia to low hyperopia, but this coordination was reduced in high myopia.

TRANSLATIONAL RELEVANCE

Greater attention should be paid to changes in astigmatism components and their coordination in high myopia.