U-shaped association between residential greenness and keratoconus.

Area of Science:

• Ophthalmology
• Environmental Health
• Epidemiology

Background:

• Keratoconus is a significant cause of blindness, primarily linked to genetic factors.
• The role of environmental influences, such as residential greenness, on keratoconus development is not well understood.

Purpose of the Study:

• To investigate the association between residential greenness and the risk of developing keratoconus.
• To explore potential environmental risk factors for this blinding corneal disorder.

Main Methods:

• A case-control study (Chinese Environment-Ocular Surface study) involving 4341 keratoconus cases and 3723 controls.
• Analysis of residential greenness using the normalized difference vegetation index (NDVI) within a 300m buffer.
• Validation using a prospective cohort study of 502,367 participants from the UK Biobank.

Main Results:

• A U-shaped association was observed between residential greenness and keratoconus.
• Increased odds of keratoconus were linked to both the lowest (OR=1.33) and highest (OR=1.54) quartiles of greenness compared to intermediate levels.
• The association was more pronounced in males, younger individuals (<24 years), and urban residents, with specific nuances for urban dwellers versus others.

Conclusions:

• Both insufficient and excessive residential greenness are associated with a higher risk of keratoconus.
• Environmental factors, specifically residential greenness, play a complex role in keratoconus etiology.
• Further research is needed to understand the mechanisms behind these associations and potential public health interventions.