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Diabetes mellitus (DM) is a global public health problem. The number of cases of DM worldwide are projected to increase to 783.2 million by the year 2045 (Sun et al., 2022). Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and the main cause of blindness among adults in the productive age-group (Wong & Sabanayagam, 2020). The estimated global prevalence of DR among diabetic patients is 35.36%(NCD-RisC, 2016). In China, the reported pooled prevalence of DR in the Chinese general population was 1.14%; among people with DM, the pooled prevalence rate was 18.45% (Song et al., 2018). The number of DM people is likely to increase due to global population aging, urbanization, rising prevalence of obesity, and sedentary lifestyle (Whiting et al., 2011).Consequently, the number of people affected by DR is also projected to increase.DR is usually asymptomatic in the early stages of the disease.Untreated DR can lead to severe impairment of vision, eventually leading to blindness (Cheung et al., 2010). Studies conducted in Shanghai, China, showed that the proportion of blindness caused by DR was only 7.6%-8.0% and that DR was fifth or sixth leading cause of blindness in 2001 -2009(Wu et al., 2011, but as high as 11.2% in