Purpose: To assess the vitreoretinal interface for the occurrence of posterior vitreous detachment after intravitreal injection of triamcinolone acetonide.

Methods: This prospective interventional study included 40 eyes of 30 patients, all of them had macular edema due to different underlying diseases: Diabetic Macular edema (n = 21) Choroidal neovascularization (n = 8), Retinal vein occlusion (n = 5), Uveitis (n = 6). All eyes were indicated to receive one or more intravitreal injections of Triamcinolone Acetonide (IVTA). Each eye was injected in a separate session with the same dose (4 mg / 0.1 ml) and same surgical technique. Then they were followed-up for six months after the last injection by fundus biomicroscopy, B-mode ultrasonography and posterior segment optical coherence tomography to detect posterior vitreous detachment. All patients completed the study at the six-month visit

Results: Posterior vitreous detachment occurred in 20 eyes (50%) out of total 40 eyes. It occurred after one month in 8 eyes, after 2 months in 4 eyes, after 3 months in 6 eyes and after 4 months in 2 eyes. It was detected after the first injection in one of four eyes (25%) that received a single injection. In eight out of sixteen eyes (50%) that received two injections, and in 11/20 of eyes that received three injections. PVD was higher in older patients, eyes with higher spherical equivalent and eyes that received more injections, p-value was found significant. There was no statistical significance as regards gender, underlying disease or laterality.

Conclusion: Intravitreal injection of triamcinolone acetonide induces posterior vitreous detachment, which affects the outcome of the underlying disease. Older age, myopic eyes and higher number of injections are correlated with higher incidence of posterior vitreous detachment.