Central corneal thickness (CCT) is associated with eye conditions including keratoconus and glaucoma. We performed a meta-analysis on >20,000 individuals in European and Asian populations that identified 16 new loci associated with CCT at genome-wide significance (P <5 x 10(-8)). We further showed that 2 CCT-associated loci, FOXO1 and FNDC3B, conferred relatively large risks for keratoconus in 2 cohorts with 874 cases and 6,085 controls (rs2721051 near FOXO1 had odds ratio (OR) = 1.62, 95% confidence interval (Cl) = 1.4-1.88, P = 2.7 x 10(-10), and rs4894535 in FNDC3B had OR = 1.47,95% Cl = 1.29-1.68, P = 4.9 x 10(-9)). FNDC3B was also associated with primary open-angle glaucoma (P = 5.6 x 10(-4); tested in 3 cohorts with 2,979 cases and 7,399 controls). Further analyses implicate the collagen and extracellular matrix pathways in the regulation of CCT.