Association between birth weight and refractive error in adulthood: a Mendelian randomisation study.

Area of Science:

• Ophthalmology
• Genetics
• Public Health

Background:

• Pathological myopia is a leading cause of global blindness.
• Conflicting evidence exists regarding the association between lower birth weight (BW) and myopia risk.
• Understanding the causal relationship is crucial for public health interventions.

Purpose of the Study:

• To estimate the causal effect of BW on refractive error using Mendelian randomization (MR).
• To investigate the linear relationship between BW and refractive error.
• To provide robust evidence on the role of BW in myopia development.

Main Methods:

• Utilized genetic variants associated with BW from large genome-wide association studies (GWAS).
• Performed one-sample and two-sample MR analyses in UK Biobank participants.
• Employed allele scores for BW as instrumental variables and conducted sensitivity analyses.

Main Results:

• Ordinary least squares (OLS) regression showed a small, positive association between BW and refractive error.
• MR analysis revealed a higher causal effect, indicating lower BW is associated with more myopic refractive error.
• Sensitivity analyses supported the causal estimates with minimal evidence of pleiotropy.

Conclusions:

• Lower BW within the normal range is causally associated with increased myopia.
• The identified causal effect on refractive error is modest but statistically significant.
• Findings contribute to understanding myopia etiology and potential preventative strategies.