Abstract
Intraocular vascular endothelial growth factor (VEGF) levels play an important role in the pathogenesis of blindness-related diseases, such as age-related macular degeneration (AMD). Here, we aimed to develop a paper-based enzyme-linked immunosorbent assay (P-ELISA) to analyze the suppression of aqueous VEGF concentrations following intravitreal injection (IVI) of anti-VEGF antibody (bevacizumab or ranibizumab). A total of 25 eyes with wet AMD, one with myopic neovascularization, and one with polypoidal choroidal vasculopathy were enrolled in this study. The limit of detection using P-ELISA was 0.03 pg/mL. Forty-six consecutive samples of aqueous humor were acquired. From all samples, 66.67% (10/15) achieved complete VEGF suppression (below the detection limit) within 5 weeks of receiving IVI of anti-VEGF antibody. Only 13.33% of samples (2/15) achieved complete VEGF suppression 5 weeks after receiving treatment. In some patients, elevated VEGF was still detected 5 weeks after receipt of anti-VEGF antibody, and all samples (10/10) were found to have elevated VEGF levels 49 days after treatment. Thus, we suggest that monthly IVI of anti-VEGF antibody may be required to ensure durable VEGF inhibition. Ultrasensitive P-ELISA can detect elevated VEGF at an earlier time point and may facilitate decision-making regarding appropriate treatment strategies.
Highlights
The prevalence of age-related macular degeneration (AMD) has gradually increased in developed countries[1,2]
Sixteen samples were obtained before intravitreal injection (IVI) of anti-vascular endothelial growth factor (VEGF) antibody, whereas 30 samples were acquired after IVI of anti-VEGF antibody, with varying post-IVI times (Fig. 3)
Conventional ELISA requires dilution of samples, which reduces the sensitivity of the analysis
Summary
The prevalence of age-related macular degeneration (AMD) has gradually increased in developed countries[1,2]. Intravitreal injection (IVI) therapy using anti-VEGF agents (e.g., aflibercept, bevacizumab, and ranibizumab) has emerged as an essential treatment strategy for tackling many forms of ocular neovascularization in AMD, polypoidal choroidal vasculopathy (PCV), and diabetic retinopathy[7,8]. VEGF has been proven to play a critical role in AMD, and suppression of VEGF levels within the eyeball after IVI of anti-VEGF antibody has been shown to restore or prevent further visual acuity impairment[9]. The optimal interval between serial monthly or bimonthly IVI anti-VEGF injection needs to be determined by examining true aqueous VEGF levels rather than by determining structural changes via SD-OCT14
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