## 1 Introduction  
In Korea, advancements in medical technology and improvements in living standards have led to an increase in average life expectancy, resulting in a steady rise in the middle-aged and elderly population. According to data from Statistics Korea, the proportion of individuals aged 65 and older was 15.7% in 2020 and increased to 19.2% in 2024 [1]. At the same time, the middle-aged population is also growing, and the prevalence of metabolic diseases such as diabetes [2], hypertension, dyslipidemia, and obesity has been increasing from middle age onward. Additionally, among individuals aged 65 and older, the prevalence of both metabolic diseases and age-related eye diseases has been rising. According to Statistics Korea, the proportion of people with at least one chronic disease was 19.7% in 2019 and increased to 20.5% in 2020 [3]. Middle age is a period of progressive aging, during which the risk of developing metabolic diseases may increase if lifestyle habits are not properly managed [4]. The increasing prevalence of metabolic diseases and age-related eye diseases not only affects individual health but also leads to a decline in quality of life [5]. Some studies suggest that inflammatory responses triggered by unhealthy lifestyle habits contribute to an increased risk of metabolic diseases [6] which, in turn, further promote oxidative stress and inflammation in the body [6]. In particular, poor dietary habits and lack of physical activity can lead to metabolic diseases such as diabetes [7], hypertension [8], dyslipidemia [9], and obesity [10]. These conditions weaken the body's antioxidant defense system, promote excessive production of reactive oxygen species (ROS), and ultimately cause oxidative damage. Oxidative stress damages cells and tissues, activates inflammatory responses, and sustains a state of chronic inflammation [11]. This vicious cycle not only accelerates metabolic disorders but is also closely linked to diseases caused by oxidative stress, such as cataracts. Therefore, understanding the mechanisms underlying the interaction between inflammation, metabolic diseases, and cataracts is essential. Age-related eye diseases include cataracts, glaucoma, macular degeneration, and diabetic retinopathy, with cataracts being the most common. The development of cataracts is influenced by factors such as ultraviolet (UV) exposure [12], smoking [13], alcohol consumption [14], and quality of life [5]. Oxidative stress is also known to play a key role in the prevalence of cataracts [11]. It is a critical factor in the onset and progression of cataracts, as it causes continuous oxidative damage to the eye's lens, leading to inflammation. Prolonged inflammatory responses have been reported to contribute to cataract development [11]. Some research suggests that the antioxidant nutrients vitamins C and E play a crucial role in protecting the eye from oxidative damage caused by UV exposure [15]. Antioxidants help neutralize ROS, reduce oxidative damage, and support eye health [10]. Therefore, ensuring adequate antioxidant nutrient intake among middle-aged and older adults is essential for cataract prevention, emphasizing the need for practical dietary strategies to promote sufficient antioxidant consumption. The dietary inflammatory index (DII) is a comprehensive measure that evaluates the impact of various foods and nutrients on inflammation in the body. It assesses the overall inflammatory potential of a diet by scoring foods based on their ability to promote or suppress inflammation [16]. A lower DII score, indicating a diet rich in anti-inflammatory foods, has been reported to help reduce inflammation and promote overall health [15]. Managing inflammation levels through dietary intake has been associated with the prevention of various chronic diseases [17]. Moreover, recent studies suggest that a higher DII is linked to an increased prevalence of age-related eye diseases [6; 18].