Objective To discuss the imaging ability of different anterior optical coherence tomography (OCT) systems.Methods It was a cross-sectional study.Six normal volunteers (12 eyes,24 directions) were involved in this cross-sectional study.Three different OCT systems were used to acquire images of their eyes.The important structures:scleral spur,Schlemm's canal,anterior segment angle recess and Schwalbe line were defined.The trabecular-iris angle (TIA500),angle opening distance at 500 μm (AOD500),the area of the trabeculo-iris space at 500 μm (TISA500),the widest diameter of Schlemm's canal,and the area and circumference of Schlemm's canal were measured if possible.Results Using real-time Fourier-domain anterior segment OCT,the scleral spur,Schlemm's canal,anterior segment angle recess and the Schwalbe line were defined in 8 eyes (67％) 13 positions (54％),12 eyes (100％) 22 positions (92％),12 eyes (100％) 24 positions (100％),and 6 eyes (50％) 9 positions (38％),respectively.Using RTV-ue 100 OCT,Schlemm's canal and the Schwalbe line could be defined in 8 eyes (67％) 8 positions (33％) and 10 eyes (83％) 19 positions (79％),respectively.The scleral spur and anterior segment angle recess could not be seen.The scleral spur and anterior segment angle recess were defined in 12 eyes (100％) 21 positions (88％) and 12 eyes (100％) 24positions (100％),respectively using Visante OCT,but Schwalbe's line and Schlemm's canal could not be defined.There was a significant difference in their ability to define important structures (scleral spur,P＜0.01; Schlemm's canal,P＜0.01; anterior segment angle recess,P＜0.01; and Schwalbe line,P＜0.01).The TIA500,AOD500 and TISA500 measured by Real-time Fourier-domain anterior segment OCT and Visante OCT were similar,and the area and widest diameter of Schlemm's canal measured by Real-time Fourier-domain anterior segment OCT and RTV-ue 100 OCT were also similar.The differences were not significant.Conclusion All three OCTs can acquire clear images of the anterior segment angle.Real-time Fourier-domain anterior segment OCT and RTV-ue 100 OCT can acquire high-resolution images and are good at imaging subtle structures.Real-time Fourier-domain anterior segment OCT and Visante OCT are good at imaging deep structures.