Physical characteristics of ocular structures in Chinese children with emmetropia

To evaluate whether accommodation has effects on eye elongation.

Two hundred seventy-three eyes with a refractive error between +1.0 and -0.5 diopters were divided into three groups: pre-school children, grade-school children, and middle-school children. Ocular structures were measured using autorefraction and A-scan ultrasonography.

There was a negative correlation between age and corneal power (r = -0.227, P = .0001), lens thickness (r = -0.263, P = .00001), and Gullstrand lens power (r = -0.452, P << .0001). There was a positive correlation between age and axial length (r = -0.432, P << .0001) and vitreous chamber depth (r = 0.505, P << .0001). Mean corneal power (P < .001) and lens power (P < .001) were significantly greater in pre-school children than in grade-school children, whereas axial length (P < .001) and vitreous chamber depth (P < .001) were greater in grade-school children. Mean lens thickness (P = .01) and lens power (P = .07) were higher in grade-school children than in middle-school children, whereas axial length (P = .024) and vitreous chamber depth (P < .001) were higher in middle-school children.

Ocular structures may play different roles in maintaining emmetropia. Accommodation during near work and its potential attendant hyperopic defocus could potentially drive eye elongation.