A longitudinal study of the association between visual impairment and income change using a national health screening cohort

We evaluated the influence of visual impairment (VI) on income change using the longitudinal database of a Korean National Health Insurance Service cohort. A total of 5292 participants ≥ 40 years old and registered as visually impaired persons were selected at a 1:4 ratio with 45,081 non-VI participants matched for age, sex, and income level. The income level of both the VI and non-VI groups increased over time. In the VI group, the income levels 3, 4 and 5 years were higher than the initial value, while the income levels from 1 through 5 years were increased each year in the non-VI group. The rate of change in income between time and VI were significant. In the subgroup analysis considering age, sex, and severity of VI, the rate of change in income were significant in < 65 years old subgroups. Regarding the severity of VI, a significant interaction was found for the mild-to-moderate VI subgroup. Although both the VI and non-VI groups showed increased income levels over 5 years, the degree of income increase in the VI group was relatively lower than that in the non-VI group. This finding was prominent in the middle-age subgroup. These results strongly suggested that VI induced an income inequality.