As discussed above, corticosteroids have been experimentally shown to down regulate VEGF production and possibly reduce breakdown of the blood-retinal barrier. Similarly, steroids have anti-angiogenic properties possibly due to attenuation of the effects of VEGF. Both of these steroid effects have been utilized. For example, triamcinolone acetonide is often used clinically as a periocular injection for the treatment of cystoid macular edema (CME) secondary to uveitis or as a result of intraocular surgery. In animal studies, intravitreal triamcinolone acetonide has been used in the prevention of proliferative vitreoretinopathy and retinal neovascularization. Intravitreal triamcinolone acetonide has been used clinically in the treatment of proliferative vitreoretinopathy and choroidal neovascularization.