PURPOSE: To investigate the risk factors and outcomes associated with hyphema after pars plana vitrectomy (PPV) with intravitreal gas injection. METHODS: A retrospective study was conducted on 252 patients (252 eyes) who underwent PPV with intravitreal gas injection between January 1, 2011, and August 30, 2023. Patients were grouped based on the presence of hyphema within one week postoperatively. We analyzed the clinical characteristics of the patients, surgical procedures, and the risk factors associated with the occurrence of hyphema. RESULTS: Postoperative hyphema developed in 16 (6.3%) eyes. The hyphema group was significantly younger (54.00 ± 10.88 years vs. 61.06 ± 12.41 years, P = 0.027) compared to the non-hyphema group. Additionally, the hyphema group had a higher percentage of high myopia (68.8% vs. 19.1%, P <
0.001) and a longer surgical duration (89.00 ± 33.35 min vs. 71.00 ± 28.64 min, P = 0.017) compared to the non-hyphema group. The anatomical success rate of the primary surgery at 6 months did not differ significantly between the hyphema and non-hyphema groups (93.8% vs. 95.3%, P = 0.773). High myopia (OR, 10.014
95% CI 3.211-31.235
P <
0.001) and longer surgical duration (min) (OR, 1.019
95% CI 1.003-1.035
P = 0.019) were significantly associated with the occurrence of hyphema. CONCLUSION: High myopia and longer surgical duration were risk factors for hyphema development after PPV with intravitreal gas injection. Hyphema occurrence may not have had a significant impact on the anatomical success rate at 6 months.