Objective To investigate the optical coherence tomography(OCT) features and genetic causes of 21 patients with Bietti's crystalline dystrophy(BCD).Methods All 21 patients diagnosed of BCD(Jan,2013 to Sep,2016) were included with records of complete ophthalmologic examinations,including OCT.DNA was isolated from peripheral veinous blood.PCR and direct sequencing were used to detect possible pathogenic mutations in CYP4V2 gene.Results All patients had night blindness.Plenty of glistening intraretinal crystals...