This population-based epidemiologic study measuring IOP in South Koreans found that the mean IOP of urban residents was significantly higher than that of rural residents. Therefore, the authors conclude that regional differences must be considered in the epidemiologic study of IOP distribution.
They interviewed and examined 3,101 subjects aged 40 years and older from two areas of South Korea: Bangbae-dong in Seoul and Namil-myon, a rural agricultural area.
The mean IOP of urban residents was 14.45 ± 2.67 mmHg, compared to 13.53 ± 2.76 mmHg for rural residents (P < 0.05). There was a regional difference in mean IOP even after controlling for different demographic factors in the two areas (P < 0.05).
Multiple regression analysis showed a positive correlation between mean IOP and central corneal thickness, vertical cup-to-disc ratio, history of hypertension, smoking and female sex. However, IOP tended to decrease by approximately 0.2 mmHg when age increased by 10 years.
The authors posit a few possibilities to explain these results. First, the screening period differed in the two regions; it was November to February in the rural area and June to August in the urban area. Seasonal influence on IOP has not yet been determined. The other possibility could be a difference in lifestyle. A fat-free diet has been shown to reduce IOP, which may bring concomitant reduction in plasma prostaglandin levels. In the rural population, the lifestyle, including eating habits, was less westernized, and mostly based on relatively fat-free traditional Korean food. Other unidentified ocular and systemic factors may also play a role.
They conclude that regional differences in IOP distribution should be considered in the context of an epidemiologic study, and that this study’s results will help explain glaucoma-related characteristics within the South Korean population and help set target IOPs for glaucoma patients.