Objective: To evaluate the effect of intraocular pressure (IOP) on corneal endothelial cells after silicone oil tamponade. Methods: Patients (n=131) received vitrectomy with silicone oil injection in Ophthalmology Center in Second People’s Hospital of Foshan City from January 1st to September 30th 2019 were divided into the high IOP group (n=80) and normal IOP group (n=51). IOP was >21 mmHg at any time in the high IOP group and was ≤21mmHg in the normal IOP group after surgery. The values of corneal endothelial cells before filling with silicone oil and before removing silicone oil were compared.Results: The average IOP was 20.79 mmHg in the high IOP group, and 14.70 mmHg in the normal IOP group (P<0.001). The number of endothelial cells (ECD) was reduced, but the average endothelial cell area was increased (P<0.05) in both groups. The coefficient of variation of endothelial cell size in high IOP group was increased (P<0.05). ECD loss rate was 6.3% in the high IOP group and 3.5% in normal IOP group. Increased IOP within 1–6 weeks after surgery (7.1%) and IOP ≥40 mmHg (7.3%) had the greatest impact on ECD. ECD loss was correlated with IOP (r=0.176, P=0.044). Conclusion: High intraocular pressure after silicone oil filling is an important risk factor for the loss of corneal endothelial cells.Keywords intraocular pressure; corneal endothelium; silicone oil; vitrect