To evaluate lens power during the ages of ocular development in schoolchildren aged 6-12 years in Shahroud.

This cross-sectional study was conducted on schoolchildren aged 6-12 yrs in Shahroud, northeast Iran. All students underwent the measurement of uncorrected and corrected visual acuity as well as non-cycloplegic, cycloplegic, and subjective refraction. Biometry was also done for all students.

Of 6624 invited children, 5620 participated on the study. The data of 4870 children were finally analyzed after applying the inclusion and exclusion criteria. The mean age of the participants was 9.70±1.68 yrs and 2277 participants (46.02%) were girls. The mean lens power was 22.86±1.59 D in the study population. The mean ± SD lens power was 23.91±1.53 in 6-year-old children and decreased to 22.10±1.48 in children aged 12 yrs. The mean lens power was higher in girls than boys (23.48 ± 1.48 vs. 22.34 ± 1.49 D), in rural children than urban children (23.17 ± 2.29 vs. 22.83 ± 1.49 D), and in children with hyperopia (23.25 ± 1.56 D) than children with myopia or emmetropia (22.64±1.58 and 22.86±1.59 D, respectively). According to the results of a multiple linear regression model, lens thickness (β=1.59, p<0.001), anterior chamber depth (β=2.21, p<0.001), and female sex (β=0.016, p=0.015) were associated with an increase in the lens power, while axial length (β= -4.41, p<0.001), cornel power (β= -1.47, p<0.001), spherical equivalent (β= -1.50, p<0.001), and age (β= - 0.005, p=0.001) were associated with a decrease in the lens power. Axial length and sex had the highest and lowest impact on lens power, respectively.

Lens power decreased with age in children aged 6-12 years; this decreasing trend had a similar pattern in both sexes. The lens power was associated with a shorter axial length, deeper anterior chamber, higher spherical equivalent, thicker lens, and lower corneal power.