Retinal oxygen saturation in 1461 healthy children aged 7-19 and its associated factors.

PURPOSE: The aim of the present study was to investigate age-specific normative retinal oxygen saturation values and explore the associated factors in healthy Chinese school-aged children with different refractive statuses.

DESIGN: Population-based observational cross-sectional study.

METHODS: Children aged 7-19 years were enrolled. Each participant underwent a series of comprehensive ocular examinations, including axial length (AL), cycloplegic refraction and Oxymap T1 imagery following cycloplegia. The acquired oximetry images were measured, and the values of the retinal oxygen saturation parameters were calculated. The independent factors of the retinal oxygen saturation were analysed using multiple linear regression. The oxygen saturation of retinal arteries (SaO2 ) and veins (SvO2 ) as well as the differences between the arteries and veins (AVD) were measured as the main outcomes.

RESULTS: In total, 1461 participants were included in the study. The mean age of the participants was 12.1 ± 3.2 years, and 53.0% were boys. The mean SaO2 , SvO2 and AVD values were 83.7 ± 6.4%, 50.1 ± 5.4% and 33.6 ± 5.4%, respectively, and the values increased with age. Girls had higher SvO2 and lower AVD than boys (p < 0.05). The Pearson correlation coefficients among spherical equivalent (SE) and SaO2 , SvO2 and AVD were -0.372, -0.203 and -0.240, respectively (all p < 0.001), while the correlations between AL and SaO2 , SvO2 and AVD were 0.276, 0.106 and 0.221, respectively (all p < 0.001). The myopia group had significantly higher SaO2 , SvO2 and AVD than the emmetropia and hyperopia groups (p < 0.001), but the high myopia group had lower SaO2 and SvO2 than the moderate myopia group. When age, gender, body mass index (BMI), intraocular pressure (IOP) and axial length (AL) were included as factors in the multiple regression, older age was associated with higher SaO2 , SvO2 and AVD, while longer AL was associated with higher SaO2 and AVD. Gender was an independent factor predicting SvO2 , while gender and BMI were the independent factors predicting AVD. Age explained more variance than AL in SaO2 , SvO2 and AVD.

CONCLUSIONS: Our population-based study provides age-specific profiles of retinal oxygen saturation in Chinese children and adolescents. Older age and longer AL were important independent factors of increased retinal oxygen saturation.