Purpose
To correlate angiogenic cytokines in the aqueous humor with total retinal blood flow in subjects with Type 2 diabetes with non-proliferative DR (NPDR).
Methods
17 controls and 16 NPDR patients were recruited into the study. Aqueous humor was collected at the beginning of cataract surgery to assess the concentration of 14 angiogenic cytokines. Aqueous humor was analyzed using the suspension array method. Six images were acquired to assess total retinal blood flow (TRBF) using the prototype RTVue™ Doppler FD-OCT (Optovue, Inc., Fremont, CA) using a double circular scan protocol, 1 month post-surgery. At the same visit, forearm blood was collected to determine glycosylated hemoglobin (A1c).
Results
TGF-β1, TGF-β2 and PLGF were increased while FGF-1 was reduced in NPDR compared to controls (Bonferroni corrected, p<0.003 for all). TRBF was significantly reduced in the NPDR group compared to controls (33.1±9.9 vs. 43.3±5.3, p=0.002). Aqueous FGF-1 significantly correlated with TRBF in the NPDR group (r = 0.71, p = 0.01; r2 = 0.51). In a multiple regression analysis, A1c was found to be a significant predictor of aqueous TGFβ1 and FGF-1 (p=0.018 and p=0.020, respectively).
Conclusion
Aqueous angiogenic cytokines (TGF-β1, TGF-β2 and PLGF) were elevated in conjunction with a reduction in TRBF in patients with NPDR. Non-invasive measurement of TRBF may be useful for predicting aqueous FGF-1 levels and severity of vasculopathy in DR.
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