Quantitative retinal microvasculature in children using swept-source optical coherence tomography: the Hong Kong Children Eye Study

Aims To evaluate the distributions of quantitative optical coherence tomography angiography (OCT-A) metrics and its associated factors in children. Methods 1059 children aged 6-8 years were recruited from the Hong Kong Children Eye Study. All the participants underwent OCT-A with a swept-source OCT. Retinal microvasculature on superficial capillary plexus was assessed and quantified by a customised automated image analysis programme. Univariable and multiple linear regression analyses were performed to determine systemic (body mass index (BMI), waist circumference, head circumference and blood pressure), demographic and ocular (axial length (AL), macular thickness and volume, retinal nerve fibre layer (RNFL) thickness and visual acuity) variables (independent variables) associated with OCT-A metrics (dependent variables). Results In multiple linear regression analyses, enlarged foveal avascular zone area was associated with female gender (beta=0.110, p< 0.001), decreased AL (beta=-0.097, p< 0.001) and decreased central macular thickness (beta=-0.008, p< 0.001). Decreased vessel density was associated with increased BMI (beta=-4.12x10-4, p=0.006), decreased AL (beta=0.003, p< 0.001) and decreased central macular thickness (beta=7.87x10-5, p=0.001). Increased vessel diameter index was associated with female gender (beta=0.020, p=0.007) and decreased AL (beta=-0.020, p< 0.001). Decreased fractal dimension was associated with older age (beta=-0.001, p=0.008). There were no significant correlations between OCT-A metrics with visual acuity, RNFL thickness, central corneal thickness, waist circumference, head circumference and blood pressure (all p> 0.05). Conclusion Our findings provides new information on baseline morphology of retinal microvasculature and its associated factors in school children, which will be useful for interpreting OCT-A metrics and for identifying and characterising pathological changes in retinal microvasculature.