Anterior chamber and angle characteristics in Chinese children (6-11 years old) with different refractive status using swept-source optical coherence tomography

Background The anatomic structure of the anterior chamber (AC) helps to explain differences in refractive status in school-aged children and is closely associated with primary angle closure (PAC). The aim of this study was to quantify and analyze the anterior chamber and angle (ACA) characteristics in Chinese children with different refractive status by swept-source optical coherence tomography (SS-OCT). Methods In a cross-sectional observational study, 383 children from two primary schools in Shandong Province, China, underwent a complete ophthalmic examination. First, the anterior chamber depth (ACD), anterior chamber width (ACW), angle-opening distance (AOD), and trabecular-iris space area (TISA) were evaluated automatically using a CASIA2 imaging device. AOD and TISA were measured at 500, 750 mu m nasal (N1 and N2, respectively), and temporal (T1 and T2, respectively) to the scleral spur (SS). Cycloplegic refraction and axial length (AL) were then measured. According to spherical equivalent refraction (SER), the children were assigned to hyperopic (SER > 0.50D), emmetropic (-0.50D < SER <= 0.50D), and myopic groups (SER <= -0.50D). Results Out of the 383 children, 349 healthy children (160 girls) with a mean age of 8.23 +/- 1.06 years (range: 6-11 years) were included. The mean SER and AL were - 0.10 +/- 1.57D and 23.44 +/- 0.95 mm, respectively. The mean ACD and ACW were 3.17 +/- 0.24 mm and 11.69 +/- 0.43 mm. The mean AOD were 0.72 +/- 0.25, 0.63 +/- 0.22 mm at N1, T1, and 0.98 +/- 0.30, 0.84 +/- 0.27 mm at N2, T2. The mean TISA were 0.24 +/- 0.09, 0.22 +/- 0.09mm(2) at N1, T1, and 0.46 +/- 0.16, 0.40 +/- 0.14mm(2) at N2, T2. The myopic group had the deepest AC and the widest angle. Compared with boys, girls had shorter AL, shallower ACD, narrower ACW, and ACA (all p < 0.05). By Pearson's correlation analysis, SER was negatively associated with ACD, AOD, and TISA. AL was positively associated with ACD, ACW, AOD, and TISA. In the multiple regression analysis, AOD and TISA were associated with deeper ACD, narrower ACW, and longer AL. Conclusion In primary school students, the myopic eyes have deeper AC and wider angle. ACD, ACW, AOD, and TISA all increase with axial elongation. ACA is highly correlated with deeper ACD.