Hamed Momeni-Moghaddam - Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
Frida Jabbari-Azad - Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
Mojgan Pakbin - Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.
Hassan Hashemi - Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.

Purpose: To determine 4-year changes of biometric and dioptric components in Iranian children aged 7-11 years. Methods: Multi-stage stratified cluster sampling was applied to select the participants in this 4-year cohort. In each subject, the Topcon KR-8000 (Topcon Corporation, Tokyo, Japan) and the LENSTAR/BioGraph biometer (WaveLight AG, Erlangen, Germany) were used to collect the data of cycloplegic refraction and biometry, respectively. Results: Of 468 children, 251 (53.6%) were boys. Comparison of spherical equivalent (SE) between the two study phases showed a marked myopic shift (p<0.001), with the mean changes being significantly higher in boys than girls (0.24 vs. 0.18 D). (p<001) Comparison of biometric changes between two phases showed that axial length (AL) and anterior chamber depth (ACD) increased by 0.49±0.05 mm and 0.12±0.02 mm, while lens thickness (LT) and lens power (LP) decreased by 0.08±0.01 mm and 1.59±0.12 D, respectively. (p<0.05) All biometric components changes were greater in boys than girls. Comparison of the changes of biometric components between different age groups showed a decreased LP, increased AL, and increased ACD in most age groups (p<0.05), while LT and SE did not change significantly in the age groups 9 and 11 years and 8 and 9 years, respectively. Conclusion: Although statistically and clinically considerable changes were seen in AL, ACD, LP, and LT in this 4-year longitudinal study of Iranian children aged 7-11 years, the changes observed in AL, ACD, and LT had a sinus rhythm. The results showed marked changes in all parameters except ACD in both sexes