Objectives: To determine the three-year changes in crystalline lens power (LP) and thickness (LT) in children and their associated factors. Methods: Schoolchildren aged 6-12 years living in Shahroud, northeast Iran were examined in 2015 and 2018. The Bennett formula was used to calculate LP. Multiple generalized estimating equations (GEE) analysis was used for data analysis. Results: Among the 8089 examined eye...