Methods and reagents for determining a subject's predisposition for refractive error based on the presence of opsin gene exon 3 splicing defects are provided. In one aspect, the invention provides methods for determining a subject's predisposition for refractive error comprising: (a) testing a biological sample obtained from the subject to determine exon 3 splicing defects in one or more opsin gene； and (b) correlating the exon 3 splicing defects in the one or more opsin gene with a predisposition for refractive error.
