GWAS were implemented using an additive linear model in BGENIE [18 (link)]. The mean thickness of each component PRC layer across the ETDRS grid was used as the input phenotype (Fig 1C). Eye-specific covariates including image quality measures obtained from the OCT machine (listed above) and refractive error (calculated as sphericalerror + 0.5 × cylindricalerror) were regressed out of thickness values for the left and right eye separately before a mean was made across the two eyes. Covariates including age, weight, sex, height, OCT machine ID and the first 20 genotype PCs were used in the model. A genome-wide significance threshold of P <5 × 10-8 was used. LD-score regression was implemented using LD SCore v1.0 [20 (link)] to obtain estimates of genomic inflation and heritability of traits.
Free full text: Click here