Purpose: Retinal vascular fractal dimension (D(f)) is a measure of the geometric complexity of the retinal microvasculature, and has been associated with diabetic retinopathy. In this study, the authors examined the relationship between blood pressure and retinal D(f) in children.
Methods: Among 1174 children aged 10 to 14 years who participated in the Singapore Cohort Study of Risk Factors for Myopia, retinal D(f) was measured from digital fundus images using a computer-based program following a standardized protocol. Blood pressure was calculated from the average of three separate measurements in a seated position.
Results: The analysis shows that retinal D(f) was normally distributed, with a mean of 1.4619 (SD, 0.0144). After adjusting for age, sex, height, and retinal arteriolar and venular caliber, smaller retinal D(f) was correlated with elevated mean arterial blood pressure (P = 0.02), diastolic blood pressure (P = 0.02), and possibly systolic blood pressure (P = 0.06).
Conclusions: Higher blood pressure in children is associated with smaller retinal D(f), reflecting rarefaction of the retinal microvasculature. Retinal fractal analysis detects early subtle microvascular effects of elevated blood pressure, and may further the understanding of the genesis of ocular and systemic vascular complications of hypertension.