Purpose. We combined a clinical grading scale and swept source anterior segment OCT to describe the successful and failed CLASS. Material and Methods. 23 patients in the successful group and 17 patients in the failed group were compared in terms of the IBAGS grades and AS-OCT findings at one, three, and twelve months postoperatively. Results. The majority in the successful group presented shallow blebs (91%, 57%, and 52% at 1M, 3M, and 12M, resp.). 59% of the failed group presented no bleb (H0 E0) from the early postoperative period with the rate increasing to 88% at 3M and 100% at 12M. The scleral lake was detected in all the successful patients. The successful group showed significantly higher rates of TDM integrity (P<0.001), IF (P<0.001), and SCF (P<0.05), but there were no significant differences in the rates of microcysts between the groups (P>0.05). We found a significant decrease in the SL anteroposterior extent (P=0.003) and SL height (P<0.001) over time, with no significant correlation between the above parameters and IOP. Conclusions. The subconjunctival bleb may be a sign of the successful CLASS when it matches the AS-OCT findings of TDM integrity, maintained scleral lake, and intrascleral fluid. A validated OCT pixel intensity measurement is required to evaluate the bleb reflectivity.