# Correlation Between Sunlight Exposure Time and Cataract Prevalence in Korean Adults
## 4 Discussion  
In this study's analysis of the difference in cataract prevalence according to the sunlight exposure and time, the proportion of subjects without cataracts in the 2-5 h sunlight exposure group was significantly higher than that of subjects with cataracts. On the other hand, in the 5 h or longer group, the proportion of subjects with cataracts was significantly higher than the proportion of subjects without cataracts. Therefore, in our study, we concluded that Korean adults are at risk of developing cataracts when the sunlight exposure time is more than 5 h. As in previous studies, it was suggested that sunlight exposure was related to cataracts for more than 5 h. An analysis of cataract prevalence according to the sunlight exposure time showed that the majority of Korean adults had nuclear cataracts (67.8%), followed by cortical cataracts (27.1%), posterior subcapsular cataracts (1.6%), and anterior subcapsular cataracts (3.5%). These results were similar to those reported by [PERSON] et al. [28]. Additionally, our study's analysis of differences in cataract incidence by sunlight exposure and gender showed that, interestingly, men exposed to sunlight for more than 5 h had a higher incidence of cataracts. However, in the case of women, the incidence of cataracts was higher in the group exposed to sunlight for 2-5 h, so a temporal difference in the occurrence of cataracts according to gender could be confirmed. This time difference also suggests that women are more vulnerable to sunlight exposure than men when it comes to cataract prevalence. In a study analyzing the prevalence of cataracts in Koreans from 2008 to 2011, the prevalence of cataracts was higher in women (42.3%) than in men (38.9%), and this is partially consistent with previous studies that included causes of environmental exposure [29]. [PERSON] et al. 's analysis of 806 patients diagnosed with age-related cataracts found that women had a higher prevalence of cataracts than men (64.0% vs. 56.1%, \(p\) < 0.004). This involved nuclear cataracts (38.9%) being the most common type, followed by cortical cataracts (21.9%) and posterior subcapsular cataracts (9.2%) [30]. According to our study, the prevalence of cataracts in Koreans was in the following order: nuclear cataract (26.3%), cortical cataract (10.5%), and posterior subcapsular cataract (1.4%). In [PERSON] et al. 's study on ultraviolet light exposure and lens opacity, the relationship between sunlight exposure and the UV-B (ultraviolet-B) component of light and lens opacity was investigated. The results showed that men experiencing higher average annual UV-B light levels were 1.36-times more likely to have more severe cortical opacities than men experiencing lower average annual UV-B light levels [19]. In [PERSON]'s study, age was the most important risk factor for cataracts, as in previous studies, and the incidence of senile cataracts was significantly higher in those aged over 49 compared to 40-49 years [31]. In our study, we performed statistical analysis for two groups around 45 years of age. The results showed that the incidence of cataracts from sunlight exposure was statistically more significantly higher in those over 45 years of age, and logistic regression analysis showed a 1.173-fold increase with age. Geriatric cataracts are the most common type in adults, starting between the ages of 45 and 50 [32]. Aging is the most important risk factor for cataracts, as structural and functional changes in the lens can promote their development [33]. This result is partially consistent with the results of our study analyzing the difference in cataract incidence with sunlight exposure and age. The results showed that both the group exposed to sunlight for 2 to 5 h and the group exposed to sunlight for more than 5 h had a statistically significantly higher incidence of cataracts after the age of 45 compared to before the age of 45.