Abstract
Purpose:
To evaluate and standardize a non-invasive technique for collecting a spontaneous vitreous reflux following intravitreal injection of anti-VEGF and to analyze inflammatory mediators and free VEGF
Methods:
Consecutive patients with diabetic macular edema (DME) and neovascular age related macular degeneration (nAMD), undergoing to anti-VEGF intravitreal injection treatment, were included in this prospective interventional study. Clinical data were recorded for the following comparisons. Tear samples (n=20) were also collected in some representative patients. Vitreous reflux (VR) was collected at the end of injection. Different sampling methods were selected and tested: Schirmer strip (n=10), Microsponge (n=10), Millipore filter (n=20) and Micropipette (n=20). VR was immediately preserved in extraction buffer for the following biochemical analysis. Total protein quantification was carried out using the Nanodrop technology and the protein profiles of the extracts were evaluated by electrophoresis. The VEGF content was measured by ELISA. Statistical analysis was performed to compare the best way of VR sampling and to correlate biochemical and clinical data (ANOVA)
Results:
60 eyes of 60 patients with DME and nAMD treated with intravitreal injection of anti-VEGF were included in the analysis. Both Micropipette aspiration and Millipore absorption of VR showed to be effective in both sampling and analysis of total protein. The quantification of VR volume showed a less estimated VR volume in Millipore reabsorption compare to the micropipette technique (50µL recovery; 10% less upon Millipore). The analysis of total protein content and protein profiles showed no significant difference between the two sampling methods. No significant tear contamination was detected upon Micropipette sampling. High total protein content was detected in few VR samples and associated with the macular disease. No difference in total protein analysis was detected between the two subgroups investigated. VEGF analysis showed a statistically significant higher value in nAMD subgroup compared to DME, slightly correlated to inflammatory status (p<0.083)
Conclusions:
This study indicates that both Millipore and Micropipette techniques were suitable for total protein and VEGF dosage in VR collection. However Micropipette, differently from Millipore, showed no conjunctival contamination
Keywords: 748 vascular endothelial growth factor •
468 clinical research methodology •
763 vitreous