Residential Greenness May Protect Against Diabetic Retinopathy

Miriam E. Tucker, for Medscape

August 12, 2022

The study covered in this summary was published in Preprints with The Lancet and has not yet been peer reviewed.

Key Takeaways

  • Study provides epidemiological evidence for significant protective effects of residential greenness on diabetic retinopathy (DR), particularly nonproliferative DR (NPDR) and macular edema.

  • Results highlight the importance of promoting greenness exposure in alleviating DR risk, especially in an era of population aging and rapid urbanization.

Why This Matters

  • DR is a leading cause of blindness.

  • Mounting evidence has linked greenness exposure to reduced risk of cardiometabolic diseases and other adverse outcomes.

Study Design

  • Data from a large-scale, cross-sectional screening survey conducted in 129 cities of 27 provincial regions of China from 2018 to 2021 among patients with diabetes.

  • Residential greenness exposure was measured as the 3-year average Normalized Difference Vegetation Index (NDVI) at a spatial resolution of 250 m.

Key Results

  • The overall prevalence of DR, NPDR, proliferative DR (PDR), microaneurysm, intraretinal hemorrhage, cotton-wool spots, and macular edema were 15.7%, 11.3%, 0.4%, 5.2%, 6.0%, 1.0%, and 1.1%, respectively.

  • Inverse associations were found between residential greenness and DR prevalence. In the fully adjusted model, the odds ratio (OR) of DR prevalence per 0.1 increase in NDVI within 250 m was 0.90.

  • Greenness was inversely associated with NPDR (OR, 0.96) but not PDR (OR, 0.99; 95% CI, 0.94 - 1.03) in the fully adjusted models.

  • Compared with exposures in the lowest tertile, exposures in the highest tertile had the smallest risk of DR (0.85; P trend < .001) and NPDR (0.91; P trend < .001).

  • The prevalence of selected retinal lesions including microaneurysm, intraretinal hemorrhage, cotton wool spots, and macular edema, were also inversely linked to greenness exposure, with corresponding odds ratios of 0.94, 0.88, 0.89, and 0.89 per 0.1 increase in NDVI within 250 m.

Limitations

  • Cross-sectional study, cannot infer causality.

  • No direct measurement of socioeconomic status.

  • Information on possible mediators such as physical activity and psychological stress were not collected.

  • Not a randomly selected sample, all-Chinese population.      

Disclosures

  • Study funding: National Natural Science Foundation of China, Shanghai Committee of Science and Technology, Shanghai Hospital Development Center, and Scientific Project of Shanghai Municipal Health Commission.

  • Author disclosures: None.

This is a summary of a preprint research study, "Residential Greenness as a Novel Protective Factor for Diabetic Retinopathy: A Nationwide Analysis in China,” written by Huixun Jia of Shanghai Jiao Tong University Department of Ophthalmology, and colleagues on Preprints with The Lancet and provided to you by Medscape. It has not yet been peer reviewed.

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