Genetic Associations of Myopia and Axial Length with Diabetic Retinopathy.

Purpose: To investigate the genetic associations of myopia and axial length (AL) with diabetic retinopathy (DR).

Methods: We performed Mendelian randomization (MR) analyses using publicly available genome-wide association study (GWAS) summary statistics. Genetic variants were used as instrumental variables. Exposures included myopia, spherical equivalent (SE) and AL. Outcomes of interest included DR, its two subtypes including severe non-proliferative DR (NPDR) and proliferative DR (PDR), and vascular endothelial growth factor (VEGF) levels. The summary statistics for DR and its subtypes were derived from the FinnGen consortium, with over 20,000 participants involved.

Results: A genetically predicted longer AL was significantly protective of PDR (per mm increase in AL: Odds ratio [OR], 0.77; 95% confidence interval [CI], 0.60 to 0.99). There were no significant causal associations of myopia, SE and AL with any DR or severe NPDR ( > 0.05 for all). After pooling the MR results from five different data sources, we found no evidence of causal relationship between AL and VEGF levels (beta, -0.01; 95% CI, -0.08 to 0.06).

Conclusion: Our results suggest a possible causal relationship between an increased AL and a reduced risk of PDR, which may provide insights into novel strategies to prevent PDR.