In the current study, we found that the prevalence of CHD in VI patients was 11.5% (154/1335), which was various according to the difference of demographic characteristics. The related risk factors of CHD included hypertension, diabetes, visual impairment and physical exercise. In addition, there were statistically significant differences between FPG and HR (< 60) in age group <65 years, and the BMI of subjects with CHD was significantly higher in age group ≥ 65 years. The results of this study add to the current literature on visual impairment from the prevalence of coronary heart disease and related risk factors in middle-aged and elderly patients with visual impairment.
We founded that whether it is in the middle-aged group or the elderly group with impaired vision, the history of hypertension and diabetes were independent risk factors for coronary heart disease, which is consistent with previous studies.18–20 We also confirmed that the increase level of fasting plasma glucose (FBG)was closely correlated with risk of CHD in < 65 years group. These consistent conclusions might suggest combined assessment of these indicators may allow the timely detection of CHD among patients with VI.
Our data also suggested that different levels of visual impairment and physical activity were closely related to coronary heart disease. Those participants with low visual impairment and mild to moderate physical activity have a lower risk of coronary heart disease. The disability with reduced vision may be a key barrier to an active lifestyle in adults, and is prominently manifested by increased sedentary behavior. Moreover, this population experiences activity limitations in walking, and environmental barriers such as transport and lack of accessible exercise equipment can hamper a person’s ability to be physically active.21,22 The visually impaired people who are blind may have more significant environmental obstacles such as walking, transportation, and accessible sports equipment, which greatly reduces their chances of participating in physical activities23,24. In addition, studies have shown that visually impaired people with sedentary habits are more likely to have multiple complications (such as hypertension and diabetes), which also greatly increases the risk of coronary heart disease.8,25,26 Healthy People 2020 objective PA-11 calls for increasing the proportion of physician office visits that include counseling or education related to physical activity. This suggests that attention should be paid to people with impaired vision who have less physical activity, especially blind people who are sedentariness.
Notably, we found that HR (< 60) was associated with CHD in the < 65 years old group. It is well accepted that atherosclerotic plaques are viscoelastic, heart rate and heart rate variability (HRV) reduction and atherosclerotic cardiovascular disease (CHD).20 A high resting heart rate is associated with an increase in cardiovascular mortality in the general population.21,22 Scientific evidence has shown that a high resting heart rate is a risk factor for the pathogenesis of atherosclerosis, while reductions in resting heart rate decreased vascular oxidative stress and prevented atherosclerosis in animal models.23 However, our investigation failed to find that the increased heart rate of the visually impaired population increases the risk of coronary heart disease. There are limited data on whether the heart rate of visually impaired people affects coronary heart disease. Future research should pay more attention to the difference in heart rate monitoring between visually impaired people and normal people as well as the underlying physiological mechanisms.
Indeed, a strong and persistent association between BMI and coronary heart disease has been reported and it is generally regarded as a predictor of cardiovascular disease. Our study further strengthened the notion that BMI was the important predictor of CHD. These findings indicate that effective control of body weight is crucial for the early prevention of coronary heart disease. The association between BMI and coronary risk is mostly mediated through its adverse effects on other major cardiovascular risk factors, mainly diabetes, blood pressure and lipids27—which explains that in the elderly group, obese people with visual impairment have a higher risk of coronary heart disease compared with normal weight. Due to differences in study populations, the generalization of this research result has been limited. To support this notion, more multiple-center collaborative study needs to be carried out in the future.
Our study has several potential limitations. First, our study uses a cross-sectional design, and thus it is impossible to infer causal and temporal relationships of risk factors with CHD. Second, our research is based on a sample of visually impaired patients from a hospital in Shanghai, China's largest city, so our findings may not be representative of the general population. Finally, due to limited data availability, we cannot consider the influence of several risk factors such as dietary habits, high-density lipoprotein cholesterol (HDL-), low-density lipoprotein cholesterol (LDL-C), psychological factors and genetic factors. Further research is needed to study the influence of these factors on CHD in VI patients.