A recent study published in Investigative Ophthalmology & Visual Science evaluated the effects of physical activity and inactivity on retinal microvasculature in children.
Give me some background.
Physical activity improves cardiovascular health in children and has been shown to affect the microvasculature, including the myocardium, skin, and retina in adults.
However: Few studies have analyzed the effects of physical activity and inactivity on the microvasculature of children.
- Further: Validated and noninvasive measures of children’s microvasculature are not widely available to address this knowledge gap.
As such: The research team of this study utilized a newly developed artificial intelligence (AI) deep learning system to measure retinal arteriolar and venular caliber in children with varying degrees of physical activity.
Tell me more about retinal microvasculature.
Changes in retinal vessel caliber (i.e., narrower arterioles and wider venules) have been associated with not only retinal pathologies, but also cardiovascular diseases like hypertension, diabetes, and coronary heart disease.
Therefore: Retinal vasculature has been suggested as a biomarker of cardiovascular health for predicting the risk of cardiovascular diseases.
Now talk about the study.
Investigators analyzed participant data from the Hong Kong Children Eye Study (HKCES), a population-based cross-sectional study of schoolchildren aged 6-8 years.
In the HKCES, participants:
- Received comprehensive ophthalmic examinations and retinal photography
- Demographic information and involvement in physical activity and inactivity were obtained from validated questionnaires
Then: A validated deep learning system was used to measure central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) from retinal photographs.
Before we go on… what are CRAE and CRVE?
To start: CRAE and CRVE reflect distinct systemic vascular physiology and disease pathways that tend to target the arterial and venous systems specifically.
CRAE is a calculated measure of the average width of retinal arterioles, and previous studies have shown that narrower CRAE was associated with:
- Higher systolic blood pressure
- Age
- Elevated high-density lipoprotein (HDL) cholesterol
Meanwhile, CRVE is a summary index indicating the average width of retinal venules; in the same study mentioned above, wider CRAE and CRVE were associated with smoking, and narrower CRVE was associated with higher HDL cholesterol.
Findings?
The final analysis included a total of 11,959 participants (52.2% male, mean age: 7.55 years).
An increased ratio of physical activity to inactivity was associated with wider CRAE (β: 1.033, P=0.007) and narrower CRVE (β: -2.079, P<0.001).
Were there any differences based on gender?
The subgroup analyses of boys and girls demonstrated that an increased ratio of physical activity to inactivity was associated with narrower CRVE in both groups (β: -2.563, P=0.001 for boys and β: -1.759, P=0.020 for girls).
However: The groups differed in that the cohort of boys was also associated with wider CRAE (β: 1.364, P=0.013), while there was no association in CRAE for girls.
Expert opinion?
The study authors noted that prior research has suggested changes in CRAE and CRVE of adults can be incorporated into existing prediction scores or used independently to predict cardiovascular disease.
”Therefore, a similar prediction score may also be developed for children,” noted the study authors.
Limitations?
These included:
- The cross-sectional design limited investigators’ ability to explore the causal and temporal relationships between retinal vessel caliber, physical activity, and inactivity
- The use of questionnaires only provided information at one timepoint and was subjected to recall bias and social desirability bias
- There may be unmeasured confounding factors, such as aerobic vs. anaerobic exercises, intensity and vigor of physical activity, socioeconomic status, etc.
- The cohort predominantly consisted of Chinese children, potentially reducing the generalizability of the findings
Take home.
These findings suggest that increased activity in children was associated with healthier microvasculature, as demonstrated with retinal photography.
This study contributes to the growing body of knowledge that physical activity positively influences vascular health from a young age.
In addition: These results underscore the potential of using retinal vasculature as a biomarker of cardiovascular health.