Outdoor artificial light at night a risk factor for exudative age-related macular degeneration

Exposure to outdoor artificial light at night (OALAN) may contribute to increased risk of developing exudative age-related macular degeneration (EAMD), as reported in a study.

For the study, researchers used the Korean National Health Insurance Service registration program database for rare and intractable diseases. They looked at 126,418 adults (mean age 66.0 years, 61.9 percent men), among whom 4,078 had newly diagnosed EAMD and 122,340 were EAMD-free matched controls.

Time-varying satellite data for a composite view of persistent nighttime illumination at an approximate scale of 1 km² were used to estimate mean levels of OALAN at participants’ residential addresses during 2008 and 2009.

In multivariable Cox proportional hazards regression analysis, an interquartile range (IQR; 55.8 nW/cm2/sr) increase in the level of OALAN exposure was associated with a 67-percent increase in the risk of incident EAMD (hazard ratio [HR], 1.67, 95 percent confidence interval [CI], 1.56–1.78).

Exposure-response curve followed a nonlinear, concave upward slope that became more pronounced at higher levels of light exposure (ie, at roughly 110 nW/cm2/sr).

Subgroup analysis showed that the positive association between OALAN and incident EAMD was observed only in urban areas (HR, 1.46, 95 percent CI, 1.33–1.61) but not in rural areas (HR, 1.01, 95 percent CI, 0.84–1.22).

The present data are consistent with the body of evidence on the negative impact of OALAN on health and warrant additional research that incorporate comprehensive information on exposure, individual adaptive behaviours, and potential mediators.