Abstract
Purpose: :
Intraviteal bevacizumab (Avastin) is frequently used for the treatment of age-related macular degeneration. Previous studies have demonstrated full thickness retinal penetration in rabbit eyes. Intravitreal recombinant microplasmin has been shown to successfully induce a posterior vitreous detachment (PVD) and vitreous liquefaction. It has been suggested that a PVD may alter the retinal penetration of intravitreally-injected molecules. The aim of this study was to evaluate avastin retinal penetration in rabbit eyes with a microplasmin-induced PVD.
Methods: :
Nine adult albino rabbits were injected with 0.1 mL of microplasmin into the left eye. Eleven days later, the rabbits were injected with 0.05 mL (1.25 mg) of Avastin into both eyes. Both eyes of three rabbits each were evaluated with immunohistochemistry to assess retinal penetration at 24 hours, three days, and seven days following the avastin injections. Scanning electron microscopy was used to confirm the presence or absence of a PVD.
Results: :
Avastin antibody labeling was observed throughout the retina in both eyes of each rabbit. Eyes that were injected with microplasmin demonstrated increased antibody labeling when compared with the contralateral eye. These findings suggest there is increased Avastin retinal penetration in eyes with a PVD. Scanning electron microscopy confirmed the presence of a PVD in microplasmin-injected eyes.
Conclusions: :
Full thickness retinal penetration is found after intravitreal Avastin injections in rabbits. Increased retinal penetration is observed in eyes with a microplasmin-induced PVD. A posterior vitreous detachment may alter the retinal penetration of Avastin which may suggest reduced dosing in eyes with a PVD.
Keywords: retina • age-related macular degeneration • immunohistochemistry