Cumulative loneliness and social isolation are associated with incident glaucoma in Chinese and US cohorts

To investigate the association of cumulative loneliness and social isolation with glaucoma risk among middle-aged and older adults in Chinese and American populations, we conducted an observational cohort study using data from the China Health and Retirement Longitudinal Study (CHARLS; n = 7,098 for loneliness and n = 8,481 for social isolation) and the Health and Retirement Study (HRS; n = 6,982 for loneliness and n = 5,011 for social isolation). Cumulative exposure was defined as reporting loneliness or social isolation at two time points (0, 1, or 2 times). In CHARLS (median follow-up: loneliness 4.90 years, social isolation 4.89 years; incident glaucoma cases: loneliness 185, social isolation 221), one-time loneliness (HR 1.49; 95% CI 1.01-2.20) and two-time loneliness (HR 1.99; 95% CI 1.39-2.86) were associated with a higher risk of self-reported incident glaucoma. Similar associations were observed for one-time social isolation (HR 1.47; 95% CI 1.01-2.15) and two-time social isolation (HR 1.77; 95% CI 1.14-2.76). In HRS (median follow-up: loneliness 4.86 years, social isolation 5.09 years; incident glaucoma cases: loneliness 566, social isolation 347), only two-time cumulative exposure was significantly associated with a higher risk of self-reported incident glaucoma: loneliness (HR 1.38; 95% CI 1.05-1.83) and social isolation (HR 1.30; 95% CI 1.01-1.66). These observational findings suggest that cumulative loneliness and social isolation may be relevant psychosocial markers for future eye-health research and should be interpreted as associative and hypothesis-generating.