Purpose: To investigate concentrations of growth factors and inflammatory cytokines in eyes with neovascular age-related macular degeneration (AMD) before and during therapy with intravitreal ranibizumab and to identify associations with disease activity.
Design: Prospective clinical trial.
Participants and controls: Twenty-eight eyes of patients with neovascular AMD were compared with 28 eyes of age-matched patients with cataract as control.
Methods: Ranibizumab was administered intravitreously once at baseline, and retreatments were given at monthly visits if optical coherence tomography (OCT) revealed macular edema or vision loss had occurred. Aqueous humor samples were taken each time intravitreal interventions were performed. Follow-up was 12 months. Luminex (Luminex Inc., Austin, TX) multiplex assays were used for measurement of 29 different growth factors and cytokines, including vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF).
Main outcome measures: Differences in the concentrations of growth factors and inflammatory cytokines in eyes with neovascular AMD compared with control eyes and the influence of therapy with intravitreal ranibizumab.
Results: A significantly increased expression of VEGF (P = 0.033) and a significantly decreased expression of PDGF (P = 0.038) were measured in the aqueous humor of eyes with neovascular AMD. Furthermore, a significant decrease of VEGF (P<0.001) was observed after intravitreal injection of ranibizumab along with significant changes in visual acuity and central retinal thickness (P = 0.039 and P<0.001). During follow-up with a flexible regimen, a correlation was identified between increased VEGF levels and persistent or recurrent macular edema. Changes in PDGF levels were strongly associated with alterations in VEGF concentration.
Conclusions: Vascular endothelial growth factor and PDGF-AA seemed to be associated with disease activity of neovascular AMD. Intravitreal anti-angiogenic treatment with ranibizumab resulted in significantly decreased intraocular VEGF expression below physiologic levels compared with controls. This effect was measurable as long as 4 weeks after each injection and was prolonged by consecutive retreatment. With recurrence after discontinuation of treatment, VEGF levels increased again.