Abstract:

Objective To study the ocular biological parameters change in school children. Design Retrospective cohort study. Participants 6 to 7 years old students, 167 cases of eye data (of the right eye).  Methods 167 cases of children were measured twice (2011, 2014) in three years for ocular biometry and refractive error. According to myopia occurrence time, children were divided into non-myopia group (both 2011 and 2014 check did not show myopia), new myopia group (those showed myopia in 2014 but no myopia in 2011 ), and myopia group (myopia was noted both in 2011 and 2014). Paired sample t test was used to compare refractive parameters changes from 2011 to 2014. The comparison between groups was done with analysis of variance (ANOVA). Main Outcome Measures Spherical equivalence (SE), axial length (AL), corneal radius (CR), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT) and axial length/corneal radius of curvature ratio (AL/CR). Results Non myopia group included 105 cases, for which there were no significant difference in SE and CR noted from 2011 to 2014 (t=0.86, -1.75; P=0.36, 0.084). However, there were significant differences in AL, CCT, ACD, LT and AL/CR (t=-19.84, -2.28, -13.94, 9.81, -8.18; P=0.000, 0.025, 0.000, 0.000, 0.000 respectively). New myopia group included 45 cases, for which from 2011 to 2014 , there was no significant difference in CR (t=-1.68，P=0.099), but there were significant changes in SE, AL, CCT, ACD, LT and AL/CR (t=13.09, -15.54, 3.37, -15.30, 11.16, -61.90; P=0.000, 0.000, 0.002, 0.000, 0.000 respectively). Myopia group included 17 cases. From 2011 to 2014, there was no significant difference in CR (t=-0.35，P=0.733), but there were significant change in SE, AL, CCT, ACD, LT and AL/CR (t=4.30, -10.70, -2.43, -3.746, 4.439, -7.95;  P=0.01, 0.000, 0.027, 0.002, 0.000, 0.000 respectively). Among the 3 groups in 2011, there were significant differences in SE, AL, ACD, LT and AL/CR (F=46.14, 8.89, 9.29, 4.47, 11.76; P=0.000, 0.000, 0.000, 0.013, 0.000 respectively); and in 2014, there were significant differences in SE, AL, ACD, LT and AL/CR (F=134.85, 24.77, 11.17, 6.63, 41.08; P=0.000, 0.000, 0.000, 0.002, 0.000). Conclusions Three-year follow-up observations indicated that the eyes in 6~7 years old children showed significant SE decrease, AL increase, CCT thickening, ACD deepen, LT thinning, AL/CR increase. LT might be an early warning signal of myopia development. (Ophthalmol CHN, 2016, 25: 106-109)

Key words: ocular biometry; , axial length/corneal radius of curvature ratio, myopia