Myopia and diabetic retinopathy: A systematic review and meta-analysis

• A meta-analysis was conducted to evaluate the association of myopia with diabetic retinopathy.
• Nine studies involving 29,231 individuals were included.
• Current studies suggest that individuals with myopia exhibit a decreased risk for developing diabetic retinopathy or vision-threatening diabetic retinopathy.
• An increased axial length plays a critical role in this protective effect.

AimsMyopia may have protective effects against diabetic retinopathy (DR). However, the data from epidemiologic studies are inconsistent. We aimed to examine the association between myopia and DR by conducting a meta-analysis.MethodsWe identified studies by searching the PubMed and EMBASE databases. Study-specific odds ratios (ORs) were pooled using a fixed or random effects model. Myopic eyes were defined as having a spherical equivalent (SE) < −0.5 diopters (D). Myopic SE, each diopter decrease in SE toward myopia, and each millimeter increase in axial length (AL) were used as independent surrogate variables for myopia.ResultsData from 6 population-based and 3 clinic-based studies were included in the analyses. Myopic SE (compared with emmetropic eyes) and each millimeter increase in AL were associated with a decreased risk for DR (pooled odds ratio [OR], 0.80 and 0.79, respectively; 95% confidence interval [CI], 0.67–0.95 and 0.73–0.86, respectively; P = 0.011 and 0.000, respectively). Each millimeter increase in AL was also associated with a decreased risk for vision-threatening diabetic retinopathy (VTDR) (pooled OR, 0.70; 95% CI, 0.60–0.82; P = 0.000). No significant association between each diopter decrease in SE and DR was observed.ConclusionsOur meta-analysis suggests that individuals with myopia exhibit a decreased risk of developing DR or VTDR. An increased AL plays a critical role in this protective effect.