[The effect of bevacizumab on the ultrastructure of choroidal neovascular membranes in patients with age-related macular degeneration (AMD)].

BACKGROUND: Age-related macular degeneration (AMD) is a disease with high social impact that severely hinders the quality of life of the affected patients. The aim of our study is to examine the ultrastructural changes in the choroidal neovascular membranes occurring after the intravitreal administration of Avastin.
MATERIAL AND METHODS: In our study we enrolled 24 AMD patients. Only 9 of them were treated with intravitreal injections of Bevacizumab (1.25 mg). Later on in all cases due to complications of the disease pars plana vitrectomy with excision of the subretinal membranes was performed. The subretinal membranes taken directly from the eye during the operation have been studied by transmission and scanning electron microscopy and with Safranin O.
RESULTS: Subretinal membranes in AMD patients consisted mainly of fibroblasts, isolated or grouped RPE cells and elements of blood. Numerous capillaries of subretinal blood vessels were also found. Their walls consisted only of one thin layer of fenestrated endothelial cells. The endothelial fenestration in the Avastin-treated patients was significantly reduced. Densely packed thrombocytes and erythrocytes occluded the capillary lumen. Some of the RPE cells showed alterations. The number of proteoglycan complexes in the matrix was significantly increased.
CONCLUSION: Our results indicate that intraviterally administered Avastin causes changes in the new vessel walls and in the extracellular matrix components. It diminishes the fenestration of the endothelial cells but also increases the risk of vessel occlusions and may have an alterating effect on the RPE cells. Although Avastin has the potential to improve the quality of life, patients subjected to the treatment should be carefully selected and constantly monitored.