Influence of blood pressure on retinal vascular caliber in young children

Objective: Prior studies have reported that blood pressure (BP) has a significant influence on retinal vascular caliber both in adults and children aged 6 years and older. This study aimed to examine the association between BP and retinal vascular caliber in Singapore Chinese preschoolers 4 to 5 years of age.

Design: Population-based, cross-sectional study.

Participants: A total of 385 eligible and healthy Singapore Chinese children 4 to 5 years of age who were recruited in The Strabismus, Amblyopia and Refractive Error Study in Singaporean Chinese Preschoolers from May 2006 through October 2008 underwent BP measurements and retinal photography.

Methods: According to standard protocols, BP was measured with an automatic Omron sphygmomanometer (Omron HEM 705 LP, Omron Healthcare, Inc., Bannockburn, IL) and a retinal photograph was obtained with a Canon 45° digital retinal camera (Model CR6-NM45, Canon, Inc., Tokyo, Japan) after pupil dilation. Anthropometric and optical biometric measurements such as height, weight, and axial length were obtained also. Information regarding sociodemographic status and child birth information was supplied by parents in either English or Chinese questionnaires.

Main outcome measures: The computer imaging program was used to measure the caliber of all retinal arterioles and venules located in zone B. The central retinal arteriolar equivalent and central retinal venular equivalent were estimated by using a revised Knudtson-Parr-Hubbard formula.

Results: The mean retinal arteriolar and venular calibers were 156.19 μm and 220.01 μm in boys and 161.97 μm and 224.22 μm in girls. Higher systolic BP was associated with narrower retinal arterioles. After adjusting for age, gender, father's education, body mass index, birth weight, axial length, and caliber of the fellow retinal vessel, each 10-mmHg increase in systolic BP was associated with 2.00 μm (95% confidence interval, 0.39-3.61; P = 0.02) of retinal arteriolar narrowing and 2.51 μm (95% confidence interval, 0.35-4.68; P = 0.02) of retinal venular widening. However, neither diastolic BP nor mean arterial BP was associated with retinal arteriolar or venular caliber.

Conclusions: In very young children 4 to 5 years of age, higher systolic BP was associated with narrower retinal arterioles and wider retinal venules. This suggests that elevated BP may affect the retinal microvasculature from early childhood.