PM_2.5 Exposure as a Risk Factor for Optic Nerve Health in Type 2 Diabetes Mellitus.

Area of Science:

• Ophthalmology
• Environmental Health
• Diabetology

Background:

• Type 2 diabetes mellitus (T2DM) is a growing global health concern.
• Diabetes is associated with various ocular complications, including optic nerve damage.
• Particulate matter (PM2.5) exposure is a known risk factor for cardiovascular and respiratory diseases, with emerging evidence linking it to neurological effects.

Purpose of the Study:

• To investigate the association between long-term exposure to fine particulate matter (PM2.5) and optic disc parameters in patients with T2DM.
• To assess the impact of PM2.5 on vertical cup-to-disc ratio (vCDR), vertical optic disc diameter (vDD), and vertical optic cup diameter (vCD).

Main Methods:

• Cross-sectional analysis of 65,750 T2DM patients from the Shanghai Cohort Study of Diabetic Eye Disease (SCODE) (2017-2018).
• Optic disc parameters were measured from fundus images.
• PM2.5 exposure was estimated using a random forest model integrating satellite and meteorological data.
• Multivariate linear regression models were used, adjusting for confounders such as age, BMI, blood pressure, glucose levels, diabetes duration, and lifestyle factors.

Main Results:

• A 10 μg/m³ increase in PM2.5 exposure was significantly associated with reductions in vCDR (-0.008), vDD (-42.547 μm), and vCD (-30.517 μm) (p < 0.001).
• These associations remained significant after sensitivity analyses and adjustments for other air pollutants (O3, NO2).

Conclusions:

• Long-term PM2.5 exposure is correlated with adverse changes in optic disc parameters among T2DM patients.
• These findings suggest a potential link between PM2.5 exposure and optic nerve atrophy in this population.
• Given the optic nerve's connection to the central nervous system, the results may imply broader neurodegenerative effects associated with air pollution.