AIM: To observe the intraocular pressure (IOP) fluctuation at the early stage of pars plana vitrectomy (PPV) and silicon oil tamponade in high myopia with rhegmatogenous retinal detachment (RRD) eyes in diabetic patients and analyze the potential risk factors and effective treatment. METHODS: One hundred consecutive diabetic patients of RRD in highly myopic eyes were retrospectively reviewed. Patients were divided into two groups: the experimental group, those who used Tobramycin Dexamethasone Eye Drops (TDED), and control group. Pre- and postoperative IOPs, retinal nerve fiber thickness (RNFL) and optic nerve head parameters were recorded before and after IOP elevation, and in the contralateral eye before the operation. Graphpad 7.01 was used for data analysis. RESULTS: IOP elevation occurred in 42 eyes within 1wk after vitrectomy in all diabetic participants. Ocular hypertension (OHTN) was observed in 31 of 53 eyes in experimental group and 11 eyes of 47 eyes in control group at the early stage after operation. Significant differences were found between groups in 5d-1wk and 1mo after vitrectomy. In addition, IOP of 39 eyes had decreased by proper treatment and 3 eyes received glaucoma filtration surgery. Compared to the optic disc parameters before IOP elevation, the average and inferior RNFL thickness were thinner and rim area decreased as well as cup volume and vertical C/D radio increased after IOP elevation. The RNFL thickness of the opposite eyes in patients with IOP elevation was found thinner than the ones who never suffered ocular hypertension. CONCLUSION: Continual use of glucocorticoid after vitrectomy is a potential risk factor of IOP elevation in high myopia with diabetes, and doubtful open angle glaucoma should be focused on its sensibility to glucocorticoid and IOP elevation.