Correlation Between Increase of Axial Length and Height Growth in Chinese School-Age Children

Abstract

Purpose: To identify the relationship between the increase in axial length (AL) and height in school-age children and explore the influence of refractive status on such a relationship.

Methods: In this 5-year cohort study, 414 Chinese children (237 boys) aged 6-9 years (mean 7.12) underwent measurements annually. AL was measured using the Lenstar; height with the children standing, without shoes; and refraction using subjective refraction without cycloplegia. Participants were divided according to the refractive status: persistent emmetropia, persistent myopia, and newly developed myopia. The measurement time points of the persistent emmetropia and persistent myopia groups were marked as T₁, T₂, T₃, T₄, and T₅. The time of myopia onset in the newly developed myopia group was marked as t ₀; the preceding time points were marked as t _-1, t _-2, and so on, and the succeeding as t ₁, t ₂, and so on. The association between increase in AL and height was analyzed using simple correlation analysis.

Results: The mean changes in AL, height, and refraction were 1.39 mm, 23.60 cm, and -1.69 D, respectively, over 5 years in all children. The increase in AL and height were positively correlated for T₁~T₂, T₁~T₃, T₁~T₄, and T₁~T₅ (r = 0.262, P < 0.001; r = 0.108, P = 0.034; r = 0.165, P = 0.001; r = 0.174, P = 0.001, respectively). The changes in AL and height in the newly developed myopia group were significantly correlated (r = 0.289, P = 0.009) after myopia onset (t ₀~t ₂).

Conclusion: The increase in AL and height were positively correlated, especially in the newly developed myopia group after myopia onset. Thus, when children grow quickly, AL elongation should be monitored.

Keywords: axial length (AL); correlation; height; myopia; school-age children.