Purpose: To report the short-term safety of dexamethasone implants to treat macular edema due to retinal vein occlusion (RVO), in eyes with treated glaucoma or ocular hypertension at baseline using an as-needed re-treatment regimen., Methods: Retrospective clinical database study from two centers using the same electronic medical record system. Extracted data included: intraocular pressure (IOP), visual acuity (VA), central 1 mm retinal thickness (CRT) by optical coherence tomography, phakic status, number of injections, glaucoma treatment, and peri-operative complications., Results: Thirty-three eyes of 33 patients on IOP-lowering treatment for glaucoma or ocular hypertension (OHT) at baseline and mean IOP of 16 mmHg at baseline received one to four (mean, 1.8; median, 1) dexamethasone implants over 18 months for RVO-related macular edema. Fourteen eyes (42 %) had IOP of ≥21 mmHg, and three eyes (9 %) had IOP of ≥35 mmHg at one or more visits during the study period. Nine of 14 eyes (64 %) with raised IOP required additional topical treatment only for a mean (SE) period of 8.5 months (3.2), while the remaining five eyes (36 %) required long-term additional IOP-lowering treatment for a mean (SE) of 16 months (1.44). Surgery for IOP lowering was not required in any eye. Mean VA (SE) improved from 44 (3) ETDRS letters at baseline to 47 letters (5) at 2 months (p = 0.049), 48 (8) letters at 6 months and 46 (4) letters at 12 months. Mean CRT (SE) improved from 530 (25) μm at baseline to 323 (27) μm at 2 months (p < 0.001), 498 (76) μm at 6 months, and 359 (25) μm at 12 months (p < 0.001)., Conclusion: The short-term IOP rise after intravitreal dexamethasone implant in eyes with glaucoma or ocular hypertension at baseline was acceptable and consistent with previous reports in patients without preexisting glaucoma. Treated OHT or glaucoma may not be a strict contraindication against the use of dexamethasone implant, but close monitoring of IOP is required.