AIM: To evaluate the outcome of the initial and the redo-surgeries for primary congenital glaucoma (PCG) correlated to its degree of severity. METHODS: A retrospective study involved patients with PCG presented between 2010 and 2018. Medical records were reviewed to assess the degree of the preoperative severity according to the intraocular pressure (IOP), corneal diameter and corneal edema. Success and failure rates were calculated for both first and redo-surgeries at 6 and 12mo respectively then correlated to the severity of the cases. RESULTS: Complete records were retrieved for 272 eyes (153 patients) with PCG: 43 eyes were mild, 136 moderate and 93 severe. Combined trabeculotomy and trabeculectomy (CTT) had the highest success rate in moderate (96.4%) and severe cases (59.3%) while trabeculotomy had the highest success rate in mild cases (96.3%). Medical records of 88 eyes (63 patients) with recurrent PCG were analyzed, most with severe presentation (59 eyes). Ahmed glaucoma valve (AGV) was used in 67 (76%) eyes and augmented trabeculectomy in 21 (24%) eyes. At 12mo, there was no statistically significant difference between both surgeries in total success rate (P=0.256). For mild cases, success rate was 100% for both surgeries. Severe cases had higher success rates following AGV (87%) than augmented trabeculectomy (20%). Preoperative severity of the disease was an independent factor affecting the failure rate in secondary trabeculectomy but not in AGV. Patients younger than 24mo had higher probabilities of failure following both redo-surgeries with hazard ratio =1.325 and 0.37 for augmented trabeculectomy and AGV respectively. CONCLUSION: Preoperative assessment of the severity of eyes with PCG helps in the selecting the optimal primary and secondary surgery. For first surgery, trabeculotomy is more effective in mild cases whereas; CTT and augmented subscleral trabeculectomy (SST) are appropriate for moderate and severe cases. AGV proved to be superior to augmented SST in severe recurrent cases.