Non-obstructive angioscopy (NOA) is used to visualize the surface of the coronary artery, and a clear visual field is obtained by injecting transparent fluid into the gap between the probing catheter and the fiber. This study examines visual field expansion by a dual infusion method, which involves an infusion from the probing and guiding catheters, and the relationships between visual grade and vessel characteristics. Thirty-two patients and thirty patients performed coronary plaque analysis with NOA using the conventional method and the novel dual infusion method, respectively. Images were blindly analyzed retrospectively. Visual fields were assessed from image slices using a 5-point scale (0 = invisible, 1 = poor, 2 = adequate, 3 = good, 4 = excellent) at 5-s intervals. The relationships between visual grade and vessel characteristics were analyzed using multiple stepwise linear regression analysis. The mean visual grade, “excellent” ratio, and “adequate” ratio were significantly higher using the dual infusion method than those obtained using the conventional method (p = 0.003, p = 0.004, and p = 0.005 respectively). The “invisible” ratio was significantly lower using the dual infusion method than the conventional method (p = 0.027). The visual field was negatively associated with the conventional method (β  = −0.154, p < 0.001), large vessels (β = −0.004, p < 0.49), bifurcation (β  = −0.205, p < 0.001), vessels with a sharp angle (β  = −0.106, p < 0.001), in-stent (β = −0.180, p < 0.001), and distal border of stent (β  = −0.075, p < 0.001); and positively associated with significant stenosis (β  = 0.072, p < 0.001) and significantly covered stents (β  = 0.050, p = 0.018). The visual field with NOA can be effectively expanded by the dual infusion method.