KC conceived the study, designed and conducted the research, analysed the data and drafted the paper; EM conducted the research, analysed the data and drafted the paper; DJ, JD, CH, NI, MS designed the research, assisted with analysis and revised the paper; GD carried out the NT-proBNP assay assisted with analysis and revised the paper; JW led the Adiponectin assay assisted with analysis and revised the paper; KC has primary responsibility for final content; all authors read and approved the final manuscript. This evidence concerns the gene NPPB and keratoconus.