Axial length for 7-8 years pupils of in Southern China.

Purpose : To assess eye axial length (AL), spherical equivalent (SE), astigmatic power, distance unaided visual acuity (UCVA), and their relationship in 7- and 8-year-old pupils in Kunming, Southern China. Methods : Grade I and grade II pupils underwent measurement of AL, UCVA, and refraction. The associations of AL with SE, UCVA and astigmatic power were studied. Results : Two hundred ninety one pupils enrolled with 50.2% girls. AL was 22.71 ± 0.61 mm in children with emmetropia (UCVA > 0.8, -0.50 < SE < +0.50D and astigmatism < 0.50D), it was 23.46 ± 2.42 mm in children with mild myopia (-1 ≤ SE < -0.50D and astigmatism < 0.50D), it was 23.96 ± 1.16 mm in children with myopia (SE < -1D and astigmatism < 0.50D), and it was 22.20 ± 1.16 mm in children with astigmatism (astigmatism ≥ 0.50D). AL was highly related to SE (r = 0.572, P < .0001) with the formula AL = 22.45-0.59*SE. Conclusion : In these 7- to 8-year old pupils, average AL was 22.88 ± 0.09 mm and average SE was -0.75 ± 0.13D. Astigmatic eyes demonstrated relative shorter AL while severe myopic eyes had the longest AL, although both had worse UCVA. One mm extra axial length corresponded to -1.69D extra myopia for 7- and 8-year-old pupils in Southern China.